Addition/Correction pubs.acs.org/JPCC
Correction to “Evaluating the Internal Structure of Core−Shell Nanoparticles Using X‑ray Photoelectron Intensities and Simulated Spectra” M. Chudzicki, W. S. M. Werner,* A. G. Shard, Y.-C. Wang, D. G. Castner, and C. J. Powell J. Phys. Chem. C, 2015, 119 (31), 17687−17696. DOI: 10.1021/acs.jpcc.5b04517
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e wish to correct some statements on pages 17689 and 17690 that pertain to information and results presented in our Figures 1 and 2. (1) The information in Figure 1 and the results in Figure 2 that are shown for Pd/Al2O3 nanoparticles (consisting of an Al2O3 core and a Pd shell) were actually obtained for Pd-shell/ Al-core nanoparticles. (2) The results in Figure 2 were obtained from SESSA simulations in which inelastic mean free paths (IMFPs) from the TPP-2M predictive formula of Tanuma et al.1 were employed, not attenuation lengths (ALs) as stated in the paper. (3) The parameter L1,a in the Shard T(NP) formula is defined by Shard2 as an attenuation length for photoelectrons from the shell in the shell material. Page 17689 and Figure 1 show L1,a values for Be/Au and Pd/Al2O3 nanoparticles that are actually IMFPs from the TPP-2M formula, not ALs. Furthermore, the L1,a (IMFP) value for Pd photoelectrons in Pd, given as 1.20 nm, should actually be 1.55 nm. (4) Evaluations of shell thicknesses, TNP, from the T(NP) formula were made with IMFPs from the TPP-2M formula, not ALs. The deviations from linearity in the right-most panels of Figure 2 (where TNP is plotted against TSESSA, the shell thicknesses used in the SESSA simulations, for Pd-shell/Al-core nanoparticles) can be interpreted as being due to the effects of elastic scattering, as stated in the manuscript. These deviations are due to the choice of using IMFPs rather than ALs in the T(NP) formula, as will be shown in a future paper. We would also like to provide the following additional information that was omitted from our paper. The SESSA simulations for the results in Figure 2 of our paper were performed for Be 1s, Au 4f7/2, Pd 3d5/2, and Al 2p3/2 photoelectrons excited by Al Kα X-rays. The X-rays were incident at an angle of 60° with respect to the surface normal and photoelectrons emitted normally from the nanoparticle surface were detected. Values of the parameter B = L1,a/L2,a in the Shard T(NP) formula were 0.856 and 0.984 for the Pd/Al and Be/Au systems, respectively. Similarly, values of the parameter C = L2,a/L2,b in the Shard T(NP) formula were 0.582 and 2.030 for the Pd/Al and Be/Au systems, respectively. Evaluations of these two parameters were made with IMFPs from the TPP-2M formula, not ALs.
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REFERENCES
(1) Tanuma, S.; Powell, C. J.; Penn, D. R. Calculations of Electron Inelastic Mean Free Paths. V. Data for 14 Organic Compounds over the 50−2000 eV Range. Surf. Interface Anal. 1994, 21, 165−176. (2) Shard, A. G. A Straightforward Method for Interpreting XPS Data from Core-Shell Nanoparticles. J. Phys. Chem. C 2012, 116, 16806− 16813. © 2016 American Chemical Society
Published: January 27, 2016 2484
DOI: 10.1021/acs.jpcc.6b00544 J. Phys. Chem. C 2016, 120, 2484−2484
