TY  - JOUR
A1  - Gaebel, Tina
A1  - Bein, Daniel
A1  - Mathauer, Daniel
A1  - Utecht, Manuel
A1  - Palmer, Richard E.
A1  - Klamroth, Tillmann
T1  - Nonlocal STM manipulation of chlorobenzene on Si(111)-7 x 7
BT  - Potentials, kinetics, and first-principles molecular dynamics calculations for open systems
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - We use quantum chemical cluster models together with constrained density STM Ph CI functional theory (DFT) and ab initio molecular dynamics (AIMD) for open system to simulate tip and rationalize nonlocal scanning tunneling microscope (STM) manipulation experiments for Philh ci chlorobenzene (PhCl) on a Si(111)-7 X 7 surface. We consider three different processes, namely, the electron-induced dissociation of the carbon-chlorine bond for physisorbed PhCl molecules at low temperatures and the electron- or hole-induced desorption of chemisorbed PhCl at 300 K. All processes can be induced nonlocally, i.e., up to several nanometers (nm) away from the injection site, in STM experiments. We rationalize and explain the experimental findings regarding the STM-induced dissociation using constrained DFT. The coupling of STM-induced ion resonances to nuclear degrees of freedom is simulated with AIMD using the Gadzuk averaging approach for open systems. From this data, we predict a 4 fs lifetime for the cationic resonance. For the anion model, desorption could not be observed. In addition, the same cluster models are used for transition-state theory calculations, which are compared to and validated against time-lapse STM experiments.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpcc.1c02612
SN  - 1932-7447
SN  - 1932-7455
VL  - 125
IS  - 22
SP  - 12175
EP  - 12184
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Goulet-Hanssens, Alexis
A1  - Utecht, Manuel
A1  - Mutruc, Dragos
A1  - Titov, Evgenii
A1  - Schwarz, Jutta
A1  - Grubert, Lutz
A1  - Bleger, David
A1  - Saalfrank, Peter
A1  - Hecht, Stefan
T1  - Electrocatalytic Z -> E Isomerization of Azobenzenes
JF  - Journal of the American Chemical Society
N2  - A variety of azobenzenes were synthesized to study the behavior of their E and Z isomers upon electrochemical reduction. Our results show that the radical anion of the Z isomer is able to rapidly isomerize to the corresponding E configured counterpart with a dramatically enhanced rate as compared to the neutral species. Due to a subsequent electron transfer from the formed E radical anion to the neutral Z starting material the overall transformation is catalytic in electrons; i.e., a substoichiometric amount of reduced species can isomerize the entire mixture. This pathway greatly increases the efficiency of (photo)switching while also allowing one to reach photostationary state compositions that are not restricted to the spectral separation of the individual azobenzene isomers and their quantum yields. In addition, activating this radical isomerization pathway with photoelectron transfer agents allows us to override the intrinsic properties of an azobenzene species by triggering the reverse isomerization direction (Z -> E) by the same wavelength of light, which normally triggers E -> Z isomerization. The behavior we report appears to be general, implying that the metastable isomer of a photoswitch can be isomerized to the more stable one catalytically upon reduction, permitting the optimization of azobenzene switching in new as well as indirect ways.
Y1  - 2017
U6  - https://doi.org/10.1021/jacs.6b10822
SN  - 0002-7863
VL  - 139
IS  - 1
SP  - 335
EP  - 341
PB  - American Chemical Society
CY  - Washington
ER  -