Article Cite This: ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Vibrational Relaxation in CO2 (1000)−CO2 Collisions Lauren V. Eckermann, Conor J. Flynn, and Karen J. Castle* Bucknell University, 1 Dent Drive, Lewisburg, Pennsylvania 17837, United States ABSTRACT: The overall rate of vibrational relaxation of symmetric stretch-excited carbon dioxide, CO2 (1000), was measured in a new laboratory experiment. A perturbation− relaxation approach was used where the (1000) vibrational state of CO2 was populated via a temperature jump, and the rate of collisional energy exchange was monitored using transient diode laser absorption spectroscopy. The rate coefficient for the overall de-excitation of this state through collisions with carbon dioxide, which includes both vibrational−vibrational and vibrational−translational pathways, was determined to be (2.9 ± 0.3) × 10−11 cm3 s−1. This work provides new information about the efficiency of the vibrational−vibrational collisional energy exchange processes involving the (1000) state, which are expected to be significantly faster than the vibrational−translational process. These results should be useful for improving non-local thermodynamic equilibrium models for CO2-rich planetary atmospheres. KEYWORDS: carbon dioxide, vibrational energy transfer, upper atmosphere, rate coefficient, non-LTE
■
INTRODUCTION In order to fully understand a planet’s climate, the energy balance of its atmosphere must be well-characterized. Planetary atmospheres are dynamic because their molecules and atoms are constantly absorbing, radiating, and transferring energy. It is possible for small regions of an atmosphere to be in thermodynamic equilibrium with their immediate surroundings, a condition known as local thermodynamic equilibrium, or LTE. Under LTE conditions, the distribution of molecular state populations is predictable based on the local kinetic temperature. While it is true that the local kinetic temperature is dependent on the rates of energy transfer between species and the rates of radiative cooling, when collisions between molecules are frequent enough, the loss of energy by radiative cooling is followed by a predictable redistribution of energy. This is the case in the lower atmospheres of the terrestrial planets Earth, Venus, and Mars. However, a condition known as non-local thermodynamic equilibrium (non-LTE) occurs at higher altitudes.1 Because of the low gas densities in upper atmospheres, molecular collisions do not occur frequently enough to allow sufficient collisional energy transfer such that vibrational state populations reach the expected equilibrium conditions at the local kinetic temperature. Non-LTE atmospheric regions can be challenging to model. Actual population distributions in a non-LTE region must be known in order to calculate the cooling rate at a given altitude, to simulate outgoing radiances, and to perform atmospheric property retrievals (pressure, temperature, concentrations) from observed IR emissions. However, accurate predictions of population distributions, and therefore accurate non-LTE models, require a detailed knowledge of each mechanism by which the local species exchange energy with their surroundings © XXXX American Chemical Society
including all of the collisional and radiative rates that will affect the region. In many cases, rate parameters for these processes are either unknown or poorly known. The accuracy of the results predicted by non-LTE models are limited by the uncertainties in the individual rate parameters. For modeling the middle and upper atmospheres of the terrestrial planets, rates of energy transfer between CO2 and O atoms are important because the process is highly efficient.2−5 In CO2rich atmospheres, the rate of energy transfer between CO2 molecules is also important because the relatively high number density of the colliding partner increases the collision frequency compared with CO2−O interactions.1 The Martian atmosphere can be used as an example to illustrate potential application of measurements such as the one presented in this work. The Martian atmosphere has been the subject of many studies since the 1970s, and recent efforts such as NASA’s MAVEN mission are shedding new light on Martian climate.6,7 In the Martian atmosphere, non-LTE conditions begin for the ν2-excited levels around altitudes of approximately 85 km, and the energy balance becomes heavily dependent on processes involving CO2.1 The CO2 vibrational state population distributions at a given altitude in the Martian upper mesosphere and lower thermosphere in some cases deviate significantly from a Boltzmann distribution.8,9 Solar radiation is absorbed by CO2 and is followed by vibrational−translational (V−T) energy exchange and vibrational−vibrational (V−V) energy exchange. V−T processes, or thermal deactivation of the Received: Revised: Accepted: Published: A
November 21, 2017 February 9, 2018 February 12, 2018 February 12, 2018 DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Article
ACS Earth and Space Chemistry
the most important processes are likely to be deactivation of CO2 through collisions with O atoms and with other CO2 molecules. In this work, we present a new measurement of the rate coefficient for vibrational relaxation of CO2 (1000) through collisions with other CO2 molecules. Table 1 lists some literature rate coefficients for V−T and V−V processes for the lowest few vibrational states of CO2 at
vibrationally excited states, result in transferring kinetic energy to the quencher. The V−V processes involve conversion to near-resonant states and are much faster than the V−T processes, especially the V−V processes involving ν3 states. Observations of IR emissions through limb sounding experiments have been used to develop non-LTE models that describe the region of the Martian atmosphere above 85 km, but their ability to correctly depict the energy budget depends significantly on accurate V−T and V−V quenching rate coefficients.10 Further motivation for precise laboratory measurement of V−V and V−T rate coefficients can be found in recent theoretical work.11−14 In an attempt to improve the kinetic models used in gas dynamics studies, calculations have employed state-to-state descriptions of relevant V−V processes for CO2 systems. Experimental measurements of V− V and V−T processes can serve as valuable calibration for the molecular dynamics work. An energy level diagram for the lower vibrational states of CO2 is given in Figure 1.1 Absorption of mid-infrared solar
Table 1. Literature Rate Coefficients for Collisional Relaxation of the Lowest Vibrational States of CO2 through Collisions with CO2 at 300 K initial state (001) (001) (001) (010) (001) (100)/(020) (100)/(020) (020) (030)
products after relaxation (010) (020) (030) (000) (020) (010) (010) (010) (020)
+ + + + + + + + +
KE KE KE KE (010) (010) (010) (010) (010)
rate (cm3 s−1)
ref
1.6 × 10−15 3 × 10−16 1.3 × 10−15 6 × 10−15 1.0 × 10−14 (1.3 ± 0.3) × 10−11 (1.2 ± 0.2) × 10−11 2.5 × 10−11 3.8 × 10−11
15 16 16 17 16 18 19 20 21
300 K. In all cases, the colliding partner is CO2. Kinetic energy (KE) is listed as a product for the V−T processes. The V−V processes result in an energy redistribution between the colliding partners, producing two new vibrational states.1 In addition to the entries in Table 1, relaxation rates for V−T processes involving some states with energy higher than (001) have been measured.20 Relaxation of some vibrational states by the 13CO2, 18OCO, and 17OCO isotopes have also been reported in the literature.19−22 There were several complicating factors in many of the early experiments focused on measuring (1000) relaxation rates. In some cases, electrical discharges were used wherein the populations of participating states would have been affected by both temperature changes and collisions with various transient species in the gas mixture.18 It is likely that multiple processes contributed to the measured rates. Experiments employing fluorescence detection avoid many of these problems. However, the proximity of the (1000), (0220), and (0200) energy levels, which are only separated by about 100 cm−1, complicate the interpretation of fluorescence data as the fluorescence signal will contain contributions from various states. Huddleston and Weitz suggested a lower limit for the rate of equilibration between the Fermi-mixed (1000) and (0200) states to be 3.5 × 10−11 cm3 s−1 and acknowledge that the (0220) state might also be collisionally coupled with these two states.19 In some cases, published literature values were measured with low precision or otherwise have large uncertainties (20% in the best case and no way to distinguish the states) due to potential complications in interpreting experimental data. Because it has been shown that these rates can sometimes have significant effects on simulations,10 any work that can help disentangle the contributing processes or reduce uncertainties in individual rate parameters will be helpful. While our experimental approach has its own unique complications (as discussed in the Conclusion), it has some distinct advantages over the previous experiments, and the results of this work provide new information about vibrational relaxation of the (1000) state by CO2. Specifically, we are able to directly monitor the population of the (1000) state, distinguished from
Figure 1. Energy level diagram for the lowest-energy CO2 vibrational levels.1 States with different angular momentum quantum number are spread over the x axis for clarity. For the vibrational states discussed in this work, solid arrows indicate states coupled by both V−T and V−V processes; the short dashed lines indicate states coupled by V−V processes, and the long dashed arrow indicates states coupled by a V− T process. Note that, in general, V−V processes may occur directly or stepwise. The most likely V−T processes involve exchange of a single quantum of energy.
radiation by CO2 in the Martian atmosphere primarily produces molecules in the (ν1ν21) levels. These relax to lower-lying bending or bending−stretching modes through collisional energy exchange, leading to significant populations in the (030) and (020) states. Due to the optically thin conditions, a significant fraction of the absorbed energy is re-emitted. Overall, a robust non-LTE model must include many pathways between many states. Non-LTE models of the Martian atmosphere, which is 96% carbon dioxide, will probably need to include bands that contribute only weakly in Earth’s atmosphere, such as the (1000) state. To improve understanding of the IR energy balance in terrestrial planetary upper atmospheres, there is a need for more laboratory measurements that reduce the uncertainty of many rate coefficients for V−T and V−V processes involving CO2. As discussed earlier, in the terrestrial planet atmospheres, B
DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Article
ACS Earth and Space Chemistry
avoid overpressurization. The O3 pressure in the reaction cell was kept constant by flowing Ar through the column and then the mixture through a needle valve. The flow rate of CO2 was varied across a data set between 0.5 and 5.0 sccm. The photochemical products from O3 dissociation include O(1D), which is rapidly quenched by the Kr bath gas.26 The O atoms are reactive but have a relatively long lifetime compared with that of the vibrational energy transfer of interest.27 Of the metastable O2 photoproducts, O2(1Δg) is quenched slowly by CO2. Vibrationally excited O2(1Δg, ν) and O2(3Σ−, ν) are quenched by the O2 flowing through the cell together with the O3 (from decomposition of O3) very efficiently.28,29 Ozone concentrations were measured periodically throughout the experiment by absorption of the 254 nm line of a mercury arc lamp as detected by a photomultiplier tube through a UV monochromator. Typically, we use about 30 mTorr O3, though the partial pressure varies a bit from one data set to another. The magnitude of the temperature jump was calculated from the O3 concentration and total reaction cell pressure and can be controlled by adjusting the O3 flow rate and pumping speed.23 Because the O3 is essentially bleached by the photolysis laser, it is not likely that there is much interference from the presence of undissociated, excited O3. We have experimentally verified that there is no significant change in the measured rate coefficient when O3 partial pressure is at 20 mTorr for a given data set versus 70 mTorr for another data set. This indicates that if a small amount of undissociated O3 is present, which would increase with increasing O3 partial pressure, it is not significantly influencing the results. A Laser Components mid-infrared tunable diode laser and a liquid-nitrogen-cooled InSb detector were used to monitor the rate of energy transfer. Figure 3 shows an example of an
the (020) states, as it undergoes vibrational relaxation through collisions with CO2 and can extract a relatively precise rate coefficient.
■
EXPERIMENTAL SECTION In previous work, our group measured the efficiency of vibrational relaxation of bend-excited carbon dioxide, by ground-state atomic oxygen, O(3P).23 This specific process was our focus because 15 μm emission by CO2(0110) is an especially important source of cooling in the atmospheres of Earth and Mars, and collision of ground-state CO2 with O(3P) is an efficient mechanism for forming CO2(0110). In addition, our group measured the temperature dependence of this vibrational energy transfer process as well as the rate coefficient for the analogous process of the 13CO2 isotope.24,25 In the present work, we use our established approach to focus on vibrational relaxation of CO2 through collisions with other CO2 molecules. A perturbation−relaxation experiment similar to the one detailed in a previous publication23 was used to measure the rate coefficient of the vibrational relaxation of CO2. Figure 2
Figure 2. Block diagram of the experimental setup. The diode laser beam is shown as a solid line and the Nd:YAG laser beam as a dashed line. The laser beams were collimated and overlapped through the length of the flow cell using parabolic and dichroic mirrors. The InSb detector was used with a preamplifier and digital oscilloscope to detect and collect the transient absorption signals. In order to determine the magnitude of the temperature jump, the laser beams were blocked periodically and a mercury lamp and photomultiplier tube were inserted for measurement of the concentration of ozone in the cell.
shows a block diagram of the experimental setup. A mixture of CO2, Kr, Ar, and O3 gases flowed through a 1 m cylindrical cell with barium fluoride windows. The gases were premixed before entering the flow cell and were pumped by a rotary vane direct drive pump. The total cell pressure was maintained somewhere between 5 and 15 Torr. Ozone was included because UV photolysis of O3 at 266 nm with a frequency-quadrupled Nd:YAG laser was used to initiate a temperature jump and populate the lowest vibrationally excited states of CO2. O3 photodissociation results in rapid heating of the local gas parcel followed by an expansion wave that radiates out from the center of the reaction cell. The magnitude of the temperature jump can be calculated from the photolysis laser energy profile and the O3 concentration according to the procedure detailed in our previous work.23 The Nd:YAG laser was pulsed with a repetition rate of 5.1 Hz and a fluence of about 18 mJ per pulse. Ozone was generated and stored on a pyrex column filled with silica gel inside a freezer at −40 °C. When the column is loaded with ozone, there is an obvious visual indicator because the silica gel will appear blue-purple. Care must be taken to maintain the column temperature when it is loaded with O3 to
Figure 3. Experimental CO2 absorption spectrum obtained with the diode laser. All of the absorption features represent ν3 → ν 3 + 1 transitions. Each spectral feature is labeled with the lower vibrational state involved in the transition and the rotational transition. Note that the ground vibrational state absorption feature is for the 18O isotope.
experimental CO2 absorption spectrum. All of the absorption features in Figure 3 represent asymmetric stretching transitions. The lower vibrational state of each transition is indicated along with the rotational transition label. The sample represents natural isotopic abundance, and note that one of the large absorption features is due to absorption by the 18OCO isotope. Spectral assignments were made by comparison with the C
DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Article
ACS Earth and Space Chemistry
Figure 4. Sample transient absorption curves at two different quencher concentrations along with their best fits to the relevant double exponential function.
HITRAN database.30 This spectrum was taken with approximately 100 mTorr of CO2 in the reaction cell. In order to determine the rate coefficient for relaxation of a particular vibrational state, the rate of collisional relaxation as a function of quencher concentration must be measured. Relaxation rates were determined by tuning the diode laser frequency to the absorption peak of the CO2 vibrational state of interest, (1000), and monitoring the time-evolving vibrational state population. The population first trends toward equilibrium at the new temperature after the temperature jump and then toward the initial conditions as the system cools off. Data acquisition was triggered by the Nd:YAG pulses controlling the temperature jump and recorded by a digital oscilloscope. It is clear from Figure 3 that the (1000) states are resolved completely with our instrumentation based on individual rovibrational transitions. Therefore, we can selectively and directly measure the rovibrational states of interest. In this study, we were able to monitor the higher vibrational states, those above (1000), to make sure that they were not being populated significantly by the temperature jump and thereby influencing the relaxation measurements.
the data due to population cascade from higher states. In addition, it should be noted that we do not expect any complications due to rotational redistribution following the temperature jump. Because the rotational states are so close in energy, they only require a few collisions to reach equilibrium following our modest temperature jump, and this happens very quickly.23 Figure 4 shows two transient absorption curves obtained at two different quencher concentrations as part of this experiment. The data were generated with the narrow bandwidth diode laser tuned to the frequency corresponding to the 16 12 16 O C O (1001) ← (1000) R(20) transition at 2341.5 cm−1. The shape of the transient curve has been documented numerous times, for example, by the Philips group.31 The fast rise is due to collisional relaxation at the perturbed temperature following the temperature jump, whereas the longer decay is due to thermal re-equilibration as the system returns to room temperature. The line on each curve was generated by fitting the data to the double exponential function I(t ) = a(e−bt − e−gt )
■
The parameter a is related to the height of the transient absorption curve; b is the rate of the fall, and g is the rate of the rise (the parameter of interest as this is the time when collisional vibrational relaxation occurs). Small deviations between the best fit lines and the data are due to the simplicity of the model. While other options were explored in the course of this work, it was determined that this model, which gives reliable and fairly precise best fit parameters, was preferable to a more complex model that yields less certain parameters. Each transient absorption curve was fit to the double exponential function using user-defined function feature of SigmaPlot. The overall relaxation rate was determined by performing a pseudo-Stern−Volmer analysis; weighted linear regression was performed on the transient rate of rise versus CO2 concentration. Rates of rise versus CO2 concentration for four independent sets of data acquired on different days are presented in Figure 5. Each of the four data sets was normalized to an intercept of zero, so that they could be combined into a
RESULTS AND DISCUSSION In this work, we have chosen to model the vibrational energy manifold as a five-state system with only the five lowest CO2 vibrational levels being populated. This includes the (0000), (0110), (0200), (0220), and (1000) states seen in Figure 1. Under our experimental conditions, the temperature jumps that shift population into higher vibrational states are generally less than 75 K. Even at a temperature jump of 100 K, only 0.12% of the population would be shifted to the highest-energy state in our five-state model. The next available energy level is the (0310) state, which is approximately 544 cm−1 above the (1000) state. If we were to include this state in our model, the population shift to the highest state due to a 100 K temperature jump would be about 0.02%. It seems very reasonable at our experimental conditions to truncate the system after the (1000) state. We saw no evidence of influence by higher states in the data and do not expect significant complications in interpreting D
DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Article
ACS Earth and Space Chemistry
Ultimately, our experimental approach will allow us to study in detail the energy exchange between all of the lowest energy vibrational states of CO2. In this work, we have chosen to focus on the (1000) state because, in many ways, it is the simplest to interpret. Because (1000) is the highest state with appreciable concentration post-temperature jump under our experimental conditions, it is straightforward to measure the net flow of energy out of this state. It will take more experiments to separate the possible relaxation pathways. In the future, we will develop approaches to model the kinetic data for states between the (1000) and the ground state in hopes of extracting more information on the contributing processes. In general, not much attention has been given to precise measurements of vibrational relaxation rates for the higher vibrational states of CO2. This work represents a step toward better quantifying self-quenching of CO2, which could be relevant for non-LTE models of planets with CO2 atmospheres. In addition, self-quenching of the less abundant isotopes of CO2 and collisional energy exchange between CO2 and O(3P) are likely to be important. These processes will be the subjects of future studies.
Figure 5. Plot of the rate of transient absorption curve rise versus quencher concentration. Data from four independent sets of data obtained on different days were normalized to a zero Stern−Volmer intercept and combined for this weighted linear regression. The slope of this plot is equal to the overall rate of relaxation of the (1000) state through collisions with CO2.
■
single plot. This step was necessary because the experimental conditions (concentration of ozone, pumping speed, total cell pressure) varied slightly from day to day. The Stern−Volmer intercept, which represents the total rate of relaxation by the bath gases, is sensitive to conditions and therefore will be different on different days. This has been discussed in our previous publications, and in that earlier work, the slope was shown to be independent of the intercept.23−25 The data obtained in this experiment further support the conclusion that the slope does not depend on the intercept. Note that each transient absorption curve represents 10000 data points, in which each has been averaged over 1000 laser shots. Each of the four data sets included approximately 10 transient absorption curves. The slope from the weighted linear fit of rate of rise versus CO2 concentration, (2.9 ± 0.3) × 10−11 cm3 s−1, represents the overall relaxation rate coefficient. The uncertainty is the standard error of the slope.
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Karen J. Castle: 0000-0003-0809-2563 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was supported by NASA’s Mars Fundamental Research Program via Award No. NNNX13AG27G. The authors would thank Rajasri Alaparthi and Robert Marchese for their assistance with the experiment.
■
■
CONCLUSION The (1000), (0220), and (0200) states are only separated by about 100 cm−1. In the previous experimental measurements for (1000) given in Table 1, the (1000) and (0200) were combined and treated as a Fermi dyad.13,14 Note that there are multiple possible pathways for collisional relaxation of the (1000) state through collisions with CO2, including both direct and stepwise processes: near-resonant population redistribution to (0200) or even (0220), a V−V pathway leading to (0110) states, and a V−T pathway. The overall relaxation rate coefficient measured in this work represents all collisional relaxation pathways and therefore contains all of these processes. The overall rate is going to be dominated by the fast V−V processes, which are expected to be several orders of magnitude larger than the V−T process. We recommend using the value of (2.9 ± 0.3) × 10−11 cm3 s−1 as the overall CO2 (1000)−CO2 vibrational relaxation rate coefficient. Our measured rate coefficient is slightly smaller than the value suggested by Huddleston and Weitz19 for the rate of equilibration between the (100) and (020) states, especially when you consider that our measurement contains multiple V− V pathways. One way of interpreting the overall rate coefficient presented herein is as an upper limit on the (100)−(020) equilibration rate.
REFERENCES
(1) López-Puertas, M.; Taylor, F. W. Non-LTE Radiative Transfer in the Atmosphere; World Scientific: Singapore, 2001. (2) Houghton, J. T. Absorption and Emission by Carbon-Dioxide in the Mesosphere. Q. J. R. Meteorol. Soc. 1970, 96, 767−770. (3) Bougher, S. W.; Hunten, D. M.; Roble, R. G. CO2 Cooling in Terrestrial Planet Thermospheres. J. Geophys. Res. 1994, 99, 14609− 14622. (4) Lopez-Puertas, M.; Lopez-Valverde, M. A. Radiative Energy Balance of CO2 non-LTE Infrared Emissions in the Martian Atmosphere. Icarus 1995, 114, 113−129. (5) Sharma, R. D.; Roble, R. G. Cooling Mechanisms of the Planetary Thermospheres: The Key Role of O Atom Vibrational Excitation of CO2 and NO. Chem. Phys. Phys. Chem. 2002, 3, 101−103. (6) James, P.; Christensen, P.; Clancy, R.; Lemmon, M.; Withers, P. In The Atmosphere and Climate of Mars; Haberle, R., Clancy, R., Forget, F., Smith, M., Zurek, R., Eds.; Cambridge University Press: Cambridge, 2017; pp 20−41. (7) NASA MAVEN Mission Overview. https://www.nasa.gov/ mission_pages/maven/overview/index.html (accessed Nov 15, 2017). (8) Kaeufl, H. U.; Rothermel, H.; Drapatz, S. Indication for Water in the Upper Atmosphere of Mars. Astron. Astrophys. 1984, 141, 430− 432. (9) Stepanova, G. I.; Shved, G. M. Radiation Transfer in the 4.3-μm Carbon Dioxide and 4.7-μm Carbon Monoxide Bands in the Atmospheres of Venus and Mars at Perturbed Local Thermodynamic Equilibrium. Astronomicheskii Zhurnal 1985, 62, 913−917. E
DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
Article
ACS Earth and Space Chemistry (10) Lopez-Valverde, M. S.; Lopez-Puertas, M.; Funke, B.; Gilli, G.; Garcia-Comas, M.; Drossart, P.; Piccioni, G.; Formisano, V. Modeling the Atmospheric Limb Emission of CO2 at 4.3 μm in the Terrestrial Planets. Planet. Space Sci. 2011, 59, 988−989. (11) Armenise, I.; Kustova, E. V. State-to-state Models for CO2 Molecules: From the Theory to an Application to Hypersonic Boundary Layers. Chem. Phys. 2013, 415, 269−281. (12) Lombardi, A.; Faginas-Lago, N.; Pacifici, L.; Grossi, G. Energy Transfer upon Collision of Selectively Excited CO2 Molecules: Stateto-State Cross Sections and Probabilities for Modelling of Atmospheres and Gaseous Flows. J. Chem. Phys. 2015, 143, 034307. (13) Lombardi, A.; Faginas-Lago, N.; Pacifici, L.; Costantini, A. Modeling of Energy Transfer From Vibrationally Excited CO2 Molecules: Cross Sections and Probabilities for Kinetic Modeling of Atmospheres, Flows, and Plasmas. J. Phys. Chem. A 2013, 117, 11430− 11440. (14) Bartolomei, M.; Pirani, F.; Laganà, A.; Lombardi, A. A Full Dimensional Grid Empowered Simulation of the CO 2 + CO2 Processes. J. Comput. Chem. 2012, 33, 1806−1819. (15) Bauer, S. H.; Caballero, J. F.; Curtis, R.; Wiesenfeld, J. R. Vibrational Relaxation Rates of CO2 (001) with Various Collision Partners for < 300 K. J. Phys. Chem. 1987, 91, 1778−1785. (16) Lepoutre, F.; Louis, G.; Manceau, H. Collisional Relaxation in CO2 between 180 and 400 K Measured by the Spectrophone Method. Chem. Phys. Lett. 1977, 48, 509−514. (17) Lunt, S. L.; Wickham-Jones, C. T.; Simpson, C. J. S. M. Rate Constants for the Deactivation of the 15 μm Band of Carbon Dioxide by the Collision Partners CH3F, CO2, N2, Ar, and Kr Over the Temperature Range 300 to 150 K. Chem. Phys. Lett. 1985, 115, 60−64. (18) Rhodes, C. K.; Kelly, M. J.; Javan, A. Collisional Relaxation of the 1000 State in Pure CO2. J. Chem. Phys. 1968, 48, 5730−5731. (19) Huddleston, R. K.; Weitz, E. A Laser-Induced Fluorescence Study of Energy Transfer Between the Symmetric Stretching and Bending Modes of CO2. Chem. Phys. Lett. 1981, 83, 174−179. (20) Orr, B. J.; Smith, I. W. M. Collision-induced Vibrational Energy Transfer in Small Polyatomic Molecules. J. Phys. Chem. 1987, 91, 6106−6119. (21) Lopez-Valverde, M. A.; Lopez-Puertas, M. A Non-Local Thermodynamic Equilibrium Radiative Transfer Model for Infrared Emissions in the Atmosphere of Mars. I. Theoretical Basis and Nighttime Populations of Vibrational Levels. J. Geophys. Res. 1994, 99, 13093−13115. (22) Shved, G. M.; Khvorostovskaya, L. E.; Potekhin, I. Y.; Dem’yanikov, A. I.; Kutepov, A. A.; Fomichev, V. I. Measurement of the Quenching Rate Constant of CO2(0110)-O Collisions and its Significance for the Thermal Regime and Radiation in the Lower Thermosphere. Atmos. Ocean. Phys. 1991, 27, 295−299. (23) Castle, K. J.; Kleissas, K. M.; Rhinehart, J. M.; Hwang, E. S.; Dodd, J. A. Vibrational Relaxation of CO2 (ν2) by Atomic Oxygen. J. Geophys. Res. 2006, 111, A09303. (24) Castle, K. J.; Black, L. A.; Simione, M. W.; Dodd, J. A. Vibrational Relaxation of CO2(ν2) by O(3P) in the 142−490 K Temperature Range. J. Geophys. Res. 2012, 117, A04310. (25) Cecchini, M. R.; Castle, K. J. Vibrational Relaxation of 13 CO2(ν2) byAtomic Oxygen. Chem. Phys. Lett. 2015, 638, 149−152. (26) Schofield, K. Rate Constants for the Gaseous Interactions of O(21 D2) and O(21 S0) − A Critical Evaluation. J. Photochem. 1978, 9, 55−68. (27) DeMore, W. B.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.; Kolb, C. E.; Molina, M. J. Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling, Eval. No. 12, JPL Publ. 97-4, 1997; Eval. No. 13: Supplement to Eval. No. 12, 2000. (28) Klatt, M.; Smith, I. W. M.; Symonds, A. C.; Tuckett, R. P.; Ward, G. N. State-Specific Rate Constants for the Relaxation of O2(X3Σg−, v = 8−11) in Collisions with O2, N2, NO2, CO2, N2O, CH4, and He. J. Chem. Soc., Faraday Trans. 1996, 92, 193−199. (29) Slanger, T. G.; Copeland, R. A. Energetic Oxygen in the Upper Atmosphere and the Laboratory. Chem. Rev. 2003, 103, 4731−4765.
(30) Gordon, I. A.; et al. The HITRAN2016 Molecular Spectroscopic Database. J. Quant. Spectrosc. Radiat. Transfer 2017, 1−66. (31) Pollock, D. S.; Scott, G. B. I.; Phillips, L. F. Rate Constant for Quenching of CO2(010) by Atomic Oxygen. Geophys. Res. Lett. 1993, 20, 727−729.
F
DOI: 10.1021/acsearthspacechem.7b00129 ACS Earth Space Chem. XXXX, XXX, XXX−XXX
