Formation of Exotic Networks of Water Clusters in Helium Droplets

Subscriber access provided by University of Newcastle, Australia

Article

Formation of Exotic Networks of Water Clusters in Helium Droplets Facilitated by the Presence of Neon Atoms Gary E. Douberly, Roger E Miller, and Sotiris S. Xantheas J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.7b00510 • Publication Date (Web): 03 Mar 2017 Downloaded from http://pubs.acs.org on March 3, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Journal of the American Chemical Society

Formation of Exotic Networks of Water Clusters in Helium Droplets Facilitated by the Presence of Neon Atoms Gary E. Douberly,*[a] Roger E. Miller,[b] and Sotiris S. Xantheas*[c] [a]

Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556

[b]

Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599

[c]

Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352

KEYWORDS: water clusters, hydrogen bond cooperativity, helium droplets, non-equilibrium clusters, kinetic control

ABSTRACT: Water clusters are formed in helium droplets via the sequential capture of monomers. One or two Neon atoms are added to each droplet prior to the addition of water. The infrared spectrum of the droplet ensemble reveals several signatures of polar, water tetramer clusters having dipole moments between 2 and 3 Debye. Comparison with ab initio computations supports the assignment of the cluster networks to non-cyclic “3+1” clusters, which are ~5.3 kcal/mol less stable than the global minimum non-polar cyclic tetramer. The (H2O)3Ne + H2O ring insertion barrier is sufficiently large, such that evaporative helium cooling is capable of kinetically quenching the non-equilibrium tetramer system prior to its rearrangement to the lower energy cyclic species. To this end, the reported process results in the formation of exotic water cluster networks that are either higher in energy than the most stable gas phase analogs or not even stable in the gas phase.

1

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Introduction A microscopic description of water remains an active research goal in molecular physics.1-4 The experimental and theoretical study of ionized5-8 and neutral9-20 gas-phase water clusters has played an important role in this endeavor. These systems have proven to be useful guides for probing the cooperative effects in liquid water.10, 21-23 Indeed the combined spectroscopic and theoretical study of the water dimer has resulted in a quantitative description of the water two-body potential.20, 24-29 Nevertheless, the cyclic structures of the first few neutral water clusters (trimer, tetramer, pentamer), hexamer (cage) and octamer (cube) global minima do not correspond to representative networks found in either liquid water or ice. In cyclic clusters, every molecule acts as a single donor/acceptor to nearest neighbors; these configurations are quite different from those present in the liquid, in which every molecule acts as both a double donor and a double acceptor to nearest neighbors. These networks are usually present either in higher lying isomers of small neutral clusters30 or in larger clusters of at least 20 water molecules, which have been recently probed spectroscopically.18 In the pioneering work by Miller and co-workers, water clusters were assembled inside helium droplets via a serial capture scheme.31 In addition to the dimer, the cyclic trimer, tetramer and pentamer clusters were observed via infrared (IR) spectroscopy of the droplet ensemble. These structures represent the global minima on the (H2O)2-5 potential energy surfaces, and they have been extensively probed in gas-phase studies.9-10, 12, 20, 24 Solventmediated cluster formation was also shown to occur under kinetic control due to the highly dissipative nature of superfluid helium, and the higher energy cyclic isomer of the water hexamer system was observed for the first time.31 Simulations of sequential ring insertion showed that water molecules insert barrierlessly into small preformed cyclic clusters to form the next largest species, at least up to the hexamer.32 Herein, we report a modified helium droplet approach that points towards a general approach for accessing the higher lying isomers of small water clusters that possess structural motifs resembling the non-cyclic transient structures within the hydrogen bonding networks of liquid water.

Results and Discussion The sequential pick-up of water molecules by helium droplets leads to the IR spectrum shown in Figure 1a. The water pick-up cell pressure is adjusted to maximize the probability for tetramer formation. Nevertheless, water pick-up is statistical,33 and bands associated with clusters up to the hexamer are observed. Numerical labels indicate the previously assigned cluster sizes. The spectrum in Figure 1b was obtained with Ne gas (~10-6 Torr) added to a pick-up cell situated upstream from the water cell. The Ne pressure is optimized for the pick-up of a

Page 2 of 8

single Ne atom. If one or two Ne atoms are doped into each droplet prior to water cluster formation, additional bands emerge between 3450 - 3650 cm-1. These previously unobserved spectral features fall in the general vicinity of the hydrogen bonded OH stretch bands of the water dimer and trimer. However, they are not observed when the spectrum is obtained with the reverse pick-up order, i.e. picking up Ne atoms second (Figure S1). Computations predict hydrogen bonded OH stretch bands of (H2O)2,3Ne complexes to be within 2 cm-1 of those associated with neat water clusters. Therefore, the qualitatively new features are not simply shifts of the water dimer and trimer bands.

Figure 1. Helium nanodroplet IR spectra of small water clusters assembled via the sequential pick up of water molecules. The numbers indicate the water cluster size as determined by the pick-up cell pressure dependence studies (see Figure 2), and the asterisks indicate new bands that appear upon introduction of a small amount of Ne to a pickup cell positioned upstream from the water pick-up cell. (a) Spectrum of neat water clusters inside helium nanodroplets. (b) Spectrum obtained under similar conditions except that Ne is added to the upstream pick-up cell, such that each droplet contains zero, one, or two Ne atoms before passing into the water pick-up cell. (c) Simulated (3+1A)-Ne spectrum computed at the CCSD(T) / aug-cc-pVDZ level with the harmonic approximation. (d) Simulated (3+1B)-Ne spectrum at the same level of theory. (e) Simulated cage-Ne spectrum at the same level of theory. The harmonic frequencies are scaled by a factor of 0.964.

A cluster size can be associated with the bands at 3506, 3555, and 3624 cm-1 by measuring the signal intensity variation as the pressure is changed in the water pickup cell. Figure 2 shows the pressure dependence curves for each band in Figure 1b. The three new bands have pressure dependences that most closely match the cyclic tetramer band at 3395 cm-1. In comparison, the trimer and

2


Page 3 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


pentamer bands grow in at lower and higher water pressures, respectively. This provides strong support for an assignment to (H2O)4Ne clusters.

Figure 2. Pick-up cell pressure dependence curves showing the relationship between the signal intensity and the pressure in the differentially pumped water pick-up cell. The red, green, olive, maroon, black, blue, yellow, cyan and pink curves correspond to the pressure dependence of bands centered at 3593, 3529, 3542, 3556, 3624, 3394, 3508, 3350 and -1 3335 cm , respectively. For all curves, the upstream pick-up -6 cell contains Neon at ~2 x 10 Torr. The size of the (H2O)nNe cluster associated with the three new bands (maroon, black and yellow curves) are determined by comparing the leading edges of the pick-up pressure curves to those for the known water dimer, trimer, tetramer, pentamer and hexamer bands. As shown in the black box, the leading edge slopes of these curves compare favorably to the pick-up pressure dependence for the cyclic tetramer (blue curve).

Previously unobserved water tetramer clusters are apparently formed in droplets containing one or two Ne atoms; therefore, we considered additional isomers on the (H2O)4 potential surface that would be consistent with the observed spectrum. In addition to the cyclic tetramer global minimum, three locally stable isomers were found, which are labeled as 3+1A, 3+1B, and cage, respectively, as shown in Figure 3. The relative energetics of (H2O)4Ne isomers are given in Table 1 at the CCSD(T)/aug-cc-pVDZ level of theory. With anharmonic zero-point energy (ZPE) included, the cage, 3+1A and 3+1B isomers are found to be 2.80, 5.43, and 5.24 kcal/mol enthalpically less favorable than the cyclic global minimum, respectively. The presence of a single Ne atom slightly shifts the relative energetics computed for the bare (H2O)4 clusters (Table S1). The (3+1)-Ne isomers are near-

ly isoenergetic and consist of a cyclic trimer species, in which one of the three ring waters (referred to as the acceptor-donor-donor water; ADD) acts as a hydrogen donor to a “dangling” water molecule. The 3+1 cluster consists of ring hydrogen bonds having lengths equal to 1.813, 1.927, and 2.018 Å. In comparison, the length of the hydrogen bonds within the cyclic tetramer are 1.777 Å, indicating a more open hydrogen bonding network for the 3+1 cluster.

Figure 3. Optimized structures of (H2O)4-Ne clusters. a) cyclic (udud)-Ne, b) cage-Ne, c) (3+1A)-Ne, d) (3+1B)-Ne.

The CCSD(T) scaled harmonic frequency calculations for the three locally stable (H2O)4Ne isomers are shown in Figures 1c-e. The patterns of predicted bands for the 3+1 isomers are in good agreement with the experimental bands assigned to (H2O)4Ne clusters. However, a band predicted near 3328 cm-1 for the cage isomer is absent in the droplet spectrum. In general, the agreement between experiment and theory is less satisfactory for the cage isomer. Computations find that complexation of (H2O)4 clusters with one or two Ne atoms leads to relatively small frequency shifts for the OH stretch oscillators (Table S2). It is useful to compare the experimental and anharmonic CCSD(T) frequency shifts (∆ν) of the OH stretch bands relative to the nearly degenerate hydrogen bonded ring vibrations of the cyclic tetramer (Table 1). There is overall excellent agreement between the 3+1A and 3+1B frequency shifts and the shifts observed experimentally, whereas there is qualitative disagreement for the cage isomer. It is therefore reasonable to assign the newly observed (H2O)4Ne spectral features to either one or both of the 3+1A,B isomers interacting with one or two Ne atoms. Specifically, the 3624 and 3555 cm-1 bands are assigned to asymmetric and symmetric OH stretching vibrations of the ADD water moiety, and the 3506 and 3402 cm-1 bands are assigned to the hydrogen bonded OH stretches of the AD ring waters. The free OH stretch re-

3



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

gion from 3710 to 3760 cm-1 is congested by bands due to the water dimer and larger clusters, and assigning bands in this region to specific, non-cyclic tetramer clusters is more difficult.

Table 1. Ab initio harmonic (ω) and anharmonic (ν) frequencies for (H2O)4Ne clusters. CCSD(T) / aug-cc-pVDZ (cm-1)

Experiment

ω

ω* a

ν

Cyclic µ = 0.02 d

3516 3526

3389 3399

3350 3354

∆ν 0 4

3+1A µ = 1.69 e ∆E0 = 5.43

3759 3678 3640 3513

3624 3546 3509 3387

3579 3513 3474 3358

229 163 124 8

229 160 111 7

3+1B µ = 3.14 ∆E0 = 5.24

3761 3675 3631 3523

3625 3543 3500 3396

3590 3519 3468 3331

240 169 118 11

229 160 111 7

Cage µ = 2.64 ∆E0 = 2.80

3776 3712 3702 3689 3442

3640 3578 3569 3556 3318

3657 3539 3532 3563 3228

307 189 182 213 -122

b

∆ν 0

c

Page 4 of 8

bracket the experimental curves, and there is near quantitative agreement between the experimental curves and the simulated average effect for isomers A and B (blue curves). These results are consistent with the conclusion that 3+1A,B isomers have overlapping OH stretch bands and that (He)nNe mediated cluster formation produces these isomers in nearly equal abundance. In combination, the electric field measurements, pick-up cell pressure curves and anharmonic CCSD(T) frequency calculations provide strong evidence for the formation of non-cyclic 3+1-type water tetramers upon the sequential addition of four water molecules to droplets containing one or two Ne atoms. In addition to the formation of these non-cyclic tetramer clusters, a significant fraction of the droplet ensemble contains the global minimum cyclic tetramer. On the basis of relative band intensities normalized to computed intensities, about 60% of all tetramers are cyclic. Some of this cyclic population results from the statistical nature of Ne pick-up, which leads to a rather large fraction of droplets that do not contain Ne atoms (~40 %).33

[a] Scaled harmonic frequencies; scale factor equals 0.964. [b] CCSD(T) anharmonic frequency shift from the lowest energy band of the nearly degenerate OH ring stretch modes of the cyclic tetramer (3350 cm-1). [c] Experimental band origin shift from the degenerate ring stretch mode of the cyclic tetramer (3395 cm-1). Band origins assigned to OH stretch vibrations of the 3+1 water tetramer are 3624, 3555, 3506, 3402, and 3395 cm-1, respectively. [d] Computed permanent electric dipole moment (Debye). [e] Anharmonic zero-point corrected CCSD(T) energy (kcal/mol) relative to the cyclic tetramer (H2O)4Ne cluster.

The electric field dependence of the 3624 cm-1 band is shown in Figure 4, providing further convincing support for the above assignments. With the laser electric field aligned parallel (perpendicular) to the applied field, the signal intensity steadily grows (diminishes) as the field is increased. As the cluster’s permanent dipole moment is oriented in the electric field, the transition dipole moment associated with the OH stretch is brought into better (poorer) alignment with the laser electric field. These results definitively show that the cluster responsible for the 3624 cm-1 band is polar and that the OH stretch vibration has an associated vibrational transition dipole moment angle (VTMA) less than 54.5 degrees.34 The electric field dependence for the non-cyclic, hydrogen bonded OH stretches of the ADD water molecules in the 3+1 isomers are simulated using the computed dipole moments (1.69 (A), 3.14 (B) Debye) and VTMAs (23.9 (A), 19.6 (B) degrees) as input.35 The simulated curves for parallel and perpendicular laser polarization alignments

Figure 4. Electric field dependence of the peak signal intensi-1 ty for the 3624 cm band. The upward trending experimental curve (black) corresponds to the variation in signal intensity when the laser polarization is aligned parallel to the applied electric field. The downward trending curve is obtained with a perpendicular polarization alignment. Simulations are shown for the electric field dependence of the (3+1A)-Ne isomer (▲) and the (3+1B)-Ne isomer () for both the parallel (black) and perpendicular (red) polarization configurations. These simulations are generated using the dipole moments and rotational constants obtained from ab initio calculations, along with the computed VTMA for the non-ring Hbonded OH stretch of the ADD water moiety. The ab initio VTMAs used for the (3+1A)-Ne and (3+1B)-Ne simulations are 23.9 and 19.6 degrees, respectively. The simulated (3+1A)-Ne

4


Page 5 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


and (3+1B)-Ne curves are averaged to give the blue curves ().

In a previous theoretical study of water cluster growth, the flexible polarizable water potential (TTM2-F) was used to map the tetramer potential surface, and the cage and 3+1 isomers were found to be locally stable and separated from the cyclic minimum by approximately 0.2 kcal/mol barriers.32 These barrier heights were somewhat insensitive to zero-point energy effects. Using the tetramer potential surface, the long range, barrierless addition of water to a preformed cyclic trimer was characterized. It was assumed that, during the course of the H2O + (H2O)3 → (H2O)4 reaction, the system only travels downhill in potential energy and does not surmount barriers on the surface. These conditions mimic somewhat cluster growth in helium droplets, assuming evaporative cooling is sufficiently fast to trap the system in local minima behind small barriers. With this assumption, the fractional yields of cyclic, 3+1 and cage tetramers are 0.76, 0.12 and 0.10, respectively.32 The simulation revealed that hydrogen bonds could be broken and reformed along downhill, barrierless paths leading directly to the cyclic tetramer, bypassing the 3+1 and cage “landing sites”. In contrast to the prediction that 22% of formation events lead directly to the cage and 3+1 structures, these isomers are not observed in the neat helium droplet water cluster spectrum. Apparently, as the fourth water molecule approaches a preformed cyclic trimer, the kinetic energy gain is incompletely quenched as the tetramer system moves to regions of lower potential energy, resulting in the exclusive production of the globally stable cyclic tetramer, despite the aforementioned barriers that are ~260 times larger than kT at the droplet temperature.36 Our results indicate that the presence of a single Ne atom in the droplet significantly alters the final product distribution for the H2O + (H2O)3 → (H2O)4 reaction. This may simply be due to an enhanced ring insertion barrier when starting from the 3+1 landing site. Qualitatively, the reaction path can be visualized by interpolating the internal coordinates between the 3+1B and cyclic tetramers, as shown in Figure S2. The location of the Ne atom in the optimized (3+1B)-Ne structure is positioned nominally along the 3+1B → cyclic reaction path. Hence, while the dimer and cyclic trimer are still formed barrierlessly, a possible explanation for the formation of noncyclic tetramers is that ring insertion of the fourth water is sterically hindered by the Ne atom attached to the cyclic trimer. This is despite the fact that the interaction between the Ne atom and the cyclic trimer is computed to be relatively weak, namely 0.37 kcal/mol. Apparently, the insertion barrier in the mixed (H2O)4Ne complex is sufficiently large, such that helium cooling is capable of quenching the system prior to its rearrangement to the lower energy cyclic species. In comparison to the 3+1 sys-

tem, the Ne atom in the optimized cage-Ne structure is positioned away from the ring insertion path, perhaps accounting for the absence of cage isomers in the IR spectrum. Of course, much of this discussion is necessarily qualitative, and a quantitative description of the cluster growth process will require high level ab initio calculations of the tetramer potential surface, including the relevant barrier heights, the effect of the Ne, and a realistic treatment of the evaporative helium cooling.37

Conclusion The attachment of a single Ne atom to water clusters is predicted to have at most a minor perturbation to their IR spectra and geometric structures. Therefore, the non-equilibrium, rare-gas templated growth procedure is potentially a promising route to the experimental spectra of locally stable water cluster structures, including those that resemble the open structural motifs present in liquid water. Indeed, the scheme employed here was inspired by gas-phase studies of benzene-water clusters,38 in which the water cluster moieties mimic the higher energy structures predicted ab initio for the neat water cluster systems. Further work is underway to determine if larger (n>4) open structures result from the sequential addition of water to (H2O)4Ne clusters. Although the spectral signatures of these species are likely to appear in the same region as the ADD hydrogen bonded stretches of the 3+1 structures, quasi-mass selective methods are being employed with laser spectroscopy to obtain the spectra of these larger clusters.

Experimental and Computational Section The details of the helium droplet isolation method39-41 and the experimental approach employed in this study are provided in the supporting information. Liquid helium droplets are formed in a continuous, cryogenic, nozzle expansion of helium gas into vacuum. Droplets consisting of ~104 He atoms, on average, cool by evaporation to 0.4 K and subsequently pass through a differentially pumped “pick-up” chamber containing a variable pressure of water vapor. As droplets traverse the pick-up zone, a statistical distribution of water capture events occurs,33 producing clusters ranging from the dimer to hexamer.31 The interaction between individual water molecules is substantially more attractive than the moleculehelium interaction. Therefore, sequential pick-up of multiple molecules leads exclusively to the formation of water clusters, and the condensation energy associated with cluster formation is dissipated by helium evaporation. Furthermore, the timescale between capture events is sufficiently long (on the order of tens of microseconds), such that the internal energy of the cluster system is completely cooled to the droplet temperature prior to the addition of the next water molecule. The droplet sizes used here are sufficiently large to dissipate the condensation energy associated with the formation of water clus-

5



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ters well beyond the tetramer. The total condensation energy of the cyclic tetramer is computed to be ~104 cm-1, which can be dissipated by the evaporation of ~2000 He atoms (5 cm-1 per atom). Neon atoms are added to the droplets either before or after water molecules by placing a second pick-up cell either upstream or downstream from the water cell. About 30% of the droplet ensemble picks up a single Ne atom, whereas ~10% pick up two. A tunable, narrow linewidth, IR optical parametric oscillator is used to vibrationally excite the helium solvated molecular clusters. Vibrational excitation followed by relaxation results in a cross-section reduction for ionization, which is measured with a quadrupole mass spectrometer. Infrared spectra are obtained by modulating the laser and processing the ion signal with a lock-in amplifier as the IR wavelength is tuned from 3150 to 3800 cm-1.42 Calculations were performed at the second order Møller-Plesset perturbation43 and Coupled Cluster with Single, Double and perturbational estimate of Triple replacements44-45 levels of theory using Dunning’s augmented correlation-consistent basis set of double zeta quality.46-47 Anharmonic frequencies are obtained at the MP2/aug-cc-pVDZ level via second order vibrational perturbation theory (VPT2).48-51 The CCSD(T) anharmonic frequencies were estimated by adding the MP2/VPT2 anharmonicities to the CCSD(T) harmonic frequencies. The calculations were performed using the Gaussian 0952 and NWCHEM53 suites of codes.

ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/jacs. Detailed experimental and computational methods, Experimental spectra versus dopant pick-up order, Computed 3+1 to cyclic tetramer interconversion. (PDF)

AUTHOR INFORMATION Corresponding Author * (GED) E-mail: [email protected]; Tele: 01-706-542-3857 (SSX) Email: [email protected]

ACKNOWLEDGEMENTS G.E.D. acknowledges support from the National Science Foundation, CHE-1054742. S.S.X. was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multi-program national laboratory operated for

Page 6 of 8

DOE by Battelle. This research also used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

REFERENCES 1. Smith, J. D.; Cappa, C. D.; Wilson, K. R.; Messer, B. M.; Cohen, R. C.; Saykally, R. J., Science 2004, 306, 851. 2. Bakker, H. J.; Skinner, J. L., Chem Rev 2010, 110, 1498. 3. Lozynski, M., Chem Phys 2015, 455, 1. 4. Henao, A.; Busch, S.; Guardia, E.; Tamarit, J. L.; Pardo, L. C., Phys. Chem. Chem. Phys. 2016, 18, 19420. 5. Headrick, J. M.; Diken, E. G.; Walters, R. S.; Hammer, N. I.; Christie, R. A.; Cui, J.; Myshakin, E. M.; Duncan, M. A.; Johnson, M. A.; Jordan, K. D., Science 2005, 308, 1765. 6. Douberly, G. E.; Walters, R. S.; Cui, J.; Jordan, K. D.; Duncan, M. A., J. Phys. Chem. A 2010, 114, 4570. 7. Heine, N.; Fagiani, M. R.; Rossi, M.; Wende, T.; Berden, G.; Blum, V.; Asmis, K. R., J. Am. Chem. Soc. 2013, 135, 8266. 8. Fournier, J. A.; Wolke, C. T.; Johnson, M. A.; Odbadrakh, T. T.; Jordan, K. D.; Kathmann, S. M.; Xantheas, S. S., J. Phys. Chem. A 2015, 119, 9425. 9. Pugliano, N.; Saykally, R. J., Science 1992, 257, 1937. 10. Cruzan, J. D.; Braly, L. B.; Liu, K.; Brown, M. G.; Loeser, J. G.; Saykally, R. J., Science 1996, 271, 59. 11. Liu, K.; Brown, M. G.; Carter, C.; Saykally, R. J.; Gregory, J. K.; Clary, D. C., Nature 1996, 381, 501. 12. Liu, K.; Brown, M. G.; Cruzan, J. D.; Saykally, R. J., Science 1996, 271, 62. 13. Liu, K.; Cruzan, J. D.; Saykally, R. J., Science 1996, 271, 929. 14. Gregory, J. K.; Clary, D. C.; Liu, K.; Brown, M. G.; Saykally, R. J., Science 1997, 275, 814. 15. Perez, C.; Muckle, M. T.; Zaleski, D. P.; Seifert, N. A.; Temelso, B.; Shields, G. C.; Kisiel, Z.; Pate, B. H., Science 2012, 336, 897. 16. Cole, W. T. S.; Farrell, J. D.; Wales, D. J.; Saykally, R. J., Science 2016, 352, 1194. 17. Richardson, J. O.; Perez, C.; Lobsiger, S.; Reid, A. A.; Temelso, B.; Shields, G. C.; Kisiel, Z.; Wales, D. J.; Pate, B. H.; Althorpe, S. C., Science 2016, 351, 1310. 18. Pradzynski, C. C.; Dierking, C. W.; Zurheide, F.; Forck, R. M.; Buck, U.; Zeuch, T.; Xantheas, S. S., Phys. Chem. Chem. Phys. 2014, 16, 26691. 19. Keutsch, F. N.; Saykally, R. J., P. Natl. Acad. Sci. USA 2001, 98, 10533. 20. Mukhopadhyay, A.; Cole, W. T. S.; Saykally, R. J., Chem. Phys. Lett. 2015, 633, 13.

6


Page 7 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


21. Perez, C.; Zaleski, D. P.; Seifert, N. A.; Temelso, B.; Shields, G. C.; Kisiel, Z.; Pate, B. H., Angew. Chem.-Int. Edit. 2014, 53, 14368. 22. Xantheas, S. S., J. Chem. Phys. 1994, 100, 7523. 23. Xantheas, S. S., Chem. Phys. 2000, 258, 225. 24. Fellers, R. S.; Leforestier, C.; Braly, L. B.; Brown, M. G.; Saykally, R. J., Science 1999, 284, 945. 25. Popkie, H.; Kistenma.H; Clementi, E., J. Chem. Phys. 1973, 59, 1325. 26. Kistenmacher, H.; Popkie, H.; Clementi, E.; Watts, R. O., J. Chem. Phys. 1974, 60, 4455. 27. Matsuoka, O.; Clementi, E.; Yoshimine, M., J. Chem. Phys. 1976, 64, 1351. 28. Jorgensen, W. L., J. Am. Chem. Soc. 1979, 101, 2011. 29. Burnham, C. J.; Xantheas, S. S., J. Chem. Phys. 2002, 116, 1479. 30. Parthasarathi, R.; Elango, M.; Subramanian, V.; Sathyamurthy, N., J. Phys. Chem. A 2009, 113, 3744. 31. Nauta, K.; Miller, R. E., Science 2000, 287, 293. 32. Burnham, C. J.; Xantheas, S. S.; Miller, M. A.; Applegate, B. E.; Miller, R. E., J. Chem. Phys. 2002, 117, 1109. 33. Lewerenz, M.; Schilling, B.; Toennies, J. P., J. Chem. Phys. 1995, 102, 8191. 34. Dong, F.; Miller, R. E., Science 2002, 298, 1227. 35. Morrison, A. M.; Flynn, S. D.; Liang, T.; Douberly, G. E., J. Phys. Chem. A 2010, 114, 8090. 36. Gutberlet, A.; Schwaab, G.; Birer, O.; Masia, M.; Kaczmarek, A.; Forbert, H.; Havenith, M.; Marx, D., Science 2009, 324, 1545. 37. Walewski, L.; Forbert, H.; Marx, D., Comput. Phys. Commun. 2014, 185, 884. 38. Pribble, R. N.; Zwier, T. S., Science 1994, 265, 75. 39. Toennies, J. P.; Vilesov, A. F., Angew. Chem.Int. Edit. 2004, 43, 2622. 40. Choi, M. Y.; Douberly, G. E.; Falconer, T. M.; Lewis, W. K.; Lindsay, C. M.; Merritt, J. M.; Stiles, P. L.; Miller, R. E., Int. Rev. Phys. Chem. 2006, 25, 15. 41. Stienkemeier, F.; Lehmann, K. K., J. Phys. B At. Mol. Cl. 2006, 39, R127. 42. Morrison, A. M.; Liang, T.; Douberly, G. E., Rev. Sci. Inst. 2013, 84, 013102.

43. Møller, C.; Plesset, M. S., Phys. Rev. 1934, 46, 0618. 44. Cizek, J., J. Chem. Phys. 1966, 45, 4256. 45. Bartlett, R. J.; Musial, M., Rev. Mod. Phys. 2007, 79, 291. 46. Dunning, T. H., J. Chem. Phys. 1989, 90, 1007. 47. Kendall, R. A.; Dunning, T. H.; Harrison, R. J., J. Chem. Phys. 1992, 96, 6796. 48. Allen, W. D.; Yamaguchi, Y.; Csaszar, A. G.; Clabo, D. A.; Remington, R. B.; Schaefer, H. F., Chem. Phys. 1990, 145, 427. 49. Clabo, D. A.; Allen, W. D.; Remington, R. B.; Yamaguchi, Y.; Schaefer, H. F., Chem. Phys. 1988, 123, 187. 50. Barone, V., J. Chem. Phys. 2004, 120, 3059. 51. Barone, V.; Carbonniere, P.; Pouchan, C., J. Chem. Phys. 2005, 122, 224308. 52. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery Jr., J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Gaussian, Inc.: Wallingford, CT, USA, 2009. 53. Valiev, M.; Bylaska, E. J.; Govind, N.; Kowalski, K.; Straatsma, T. P.; Van Dam, H. J. J.; Wang, D.; Nieplocha, J.; Apra, E.; Windus, T. L.; de Jong, W., Comput. Phys. Commu.n 2010, 181, 1477.

7



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 8

Table of Contents Graphic


8

Formation of Exotic Networks of Water Clusters in Helium Droplets

Recommend Documents