TY - JOUR
T1 - Relaxation Dynamics of Electronically Coupled Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 Monolayer-Protected Cluster Dimers
AU - Herbert, Patrick J.
AU - Yi, Chongyue
AU - Compel, W. Scott
AU - Ackerson, Christopher J.
AU - Knappenberger, Kenneth L.
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/8/23
Y1 - 2018/8/23
N2 - The electronic relaxation dynamics of photoexcited Au20(SC8H9)15-n-glyme and Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 (n-= di-, tri-, and tetra-) dimers, where glyme refers to n-ethylene glycol dimethyl ether bridging molecules, were studied using pump-probe femtosecond time-resolved transient absorption spectroscopy (fsTAS). The utilization of n-glyme molecular bridging linkers provided a method to prepare Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 dimers with control over intercluster spatial separation. A dimer-specific electronic absorption resonance was observed at 2.6 eV. Analysis of fsTAS differential spectra for dimer species revealed a pump-probe waiting time-dependent blue shift of the low energy excited-state absorption (ESA) feature, suggesting electronic relaxation into a dimer-specific excited-state. Single probe-energy differential signal amplitude analysis of the ESA feature yielded a distance-dependent growth component for the electronic relaxation dynamics with time constants of 130 ± 20, 60 ± 8, and 36 ± 6 ps for the diglyme, triglyme, and tetraglyme-bridged dimers, respectively. The increase in relaxation time was attributed to intercluster distance-dependent stabilization of dimer-specific electronic excited states. These results suggest a state-specific mechanism for intercluster electronic relaxation.
AB - The electronic relaxation dynamics of photoexcited Au20(SC8H9)15-n-glyme and Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 (n-= di-, tri-, and tetra-) dimers, where glyme refers to n-ethylene glycol dimethyl ether bridging molecules, were studied using pump-probe femtosecond time-resolved transient absorption spectroscopy (fsTAS). The utilization of n-glyme molecular bridging linkers provided a method to prepare Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 dimers with control over intercluster spatial separation. A dimer-specific electronic absorption resonance was observed at 2.6 eV. Analysis of fsTAS differential spectra for dimer species revealed a pump-probe waiting time-dependent blue shift of the low energy excited-state absorption (ESA) feature, suggesting electronic relaxation into a dimer-specific excited-state. Single probe-energy differential signal amplitude analysis of the ESA feature yielded a distance-dependent growth component for the electronic relaxation dynamics with time constants of 130 ± 20, 60 ± 8, and 36 ± 6 ps for the diglyme, triglyme, and tetraglyme-bridged dimers, respectively. The increase in relaxation time was attributed to intercluster distance-dependent stabilization of dimer-specific electronic excited states. These results suggest a state-specific mechanism for intercluster electronic relaxation.
UR - http://www.scopus.com/inward/record.url?scp=85050762442&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050762442&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.8b06144
DO - 10.1021/acs.jpcc.8b06144
M3 - Article
AN - SCOPUS:85050762442
SN - 1932-7447
VL - 122
SP - 19251
EP - 19258
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 33
ER -