TY - JOUR
T1 - Understanding the chemical contribution to the enhancement mechanism in SERS
T2 - Connection with Hammett parameters
AU - Trivedi, Dhara J.
AU - Barrow, Brendan
AU - Schatz, George C.
N1 - Funding Information:
This work was dedicated to all inspiring role models, mentors, and collaborators (such as Professor Teri W. Odom, Professor Anna I. Krylov, Professor Svetlana Kilina, and Professor Sil-vana Andreescu). Their groundbreaking scientific contributions and mentoring have inspired many students, including the authors. Their research creativity has contributed to many different phases of physical chemistry and has impacted the scientific community at large. This research was sponsored by the Department of Energy, Office of Basic Energy Sciences, Grant No. DE-SC0004752.
PY - 2020/9/28
Y1 - 2020/9/28
N2 - The enhancement mechanism due to the molecule–surface chemical interaction in surface-enhanced Raman scattering (SERS) has been characterized using a theoretical approach based on time dependent density functional theory. This includes a systematic study of the chemical mechanism (CM) to the SERS enhancement for halogen substituted benzenethiols interacting with a silver cluster. Changing the halogen on benzenethiol enables us to systematically modulate interactions between the benzenethiol ring and the metal cluster. We observe a decrease in the CM enhancement factor with an increase in the atomic number of the halogen for para-substitutions. For meta-substitutions, there is no such trend. However, the results scale linearly with the Hammett parameters for both meta and para halogens, which provides an important predictive tool for interpreting chemical enhancements. We also study the effect of solvation on the CM, showing that there is a systematic increase in enhancement with the increasing solvent dielectric constant. The correlation of CM with other properties, such as the amount of charge transfer between adsorbate and metal and the excitation energies of charge transfer states, is much less predictive than the Hammett parameter correlation.
AB - The enhancement mechanism due to the molecule–surface chemical interaction in surface-enhanced Raman scattering (SERS) has been characterized using a theoretical approach based on time dependent density functional theory. This includes a systematic study of the chemical mechanism (CM) to the SERS enhancement for halogen substituted benzenethiols interacting with a silver cluster. Changing the halogen on benzenethiol enables us to systematically modulate interactions between the benzenethiol ring and the metal cluster. We observe a decrease in the CM enhancement factor with an increase in the atomic number of the halogen for para-substitutions. For meta-substitutions, there is no such trend. However, the results scale linearly with the Hammett parameters for both meta and para halogens, which provides an important predictive tool for interpreting chemical enhancements. We also study the effect of solvation on the CM, showing that there is a systematic increase in enhancement with the increasing solvent dielectric constant. The correlation of CM with other properties, such as the amount of charge transfer between adsorbate and metal and the excitation energies of charge transfer states, is much less predictive than the Hammett parameter correlation.
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U2 - 10.1063/5.0023359
DO - 10.1063/5.0023359
M3 - Article
C2 - 33003720
AN - SCOPUS:85092452175
VL - 153
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 12
M1 - 124706
ER -