TY - JOUR
T1 - The Influence of Pd-Atom Substitution on Au25(SC8H9)18Cluster Photoluminescence
AU - Herbert, Patrick J.
AU - Tofanelli, Marcus A.
AU - Ackerson, Christopher J.
AU - Knappenberger, Kenneth L.
N1 - Funding Information:
This work was supported by awards from the National Science Foundation to K.L.K., under Grant No. CHE-1806222/CHE-1904876 and CHE-1807999. In addition, this work was supported by awards from the National Science Foundation to C.J.A. under Grant Nos. CHE-1905179 and CHE-1507646.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/4/8
Y1 - 2021/4/8
N2 - The photoluminescence (PL) of Au25(SC8H9)18 and Au24Pd(SC8H9)18 was investigated using variable-field magnetic circular photoluminescence (VH-MCPL) spectroscopy. The comparison of low-temperature (4.5 K) PL spectra measured for both nanoclusters revealed an ≈40 meV blueshift of intraband emission upon Pd substitution. Compared to that for the the Au25(SC8H9)18 cluster, the degree of circular-polarization for the Au24Pd(SC8H9)18 cluster increased for the low energy (<1.65 eV) portion of the PL spectrum, but decreased for the higher energy (>1.65 eV) spectral region. MCPL spectra included three distinct components, underlying the global PL spectrum, for both clusters. Variable-field analysis of each MCPL component revealed an increase in spin-orbit coupling (Landé g-factor) magnitudes for radiative transitions of the Pd-substituted cluster with respect to Au25(SC8H9)18. Variable-temperature (VT) PL spectroscopy yielded reduced integrated global PL intensity and increased electron-vibrational coupling for Au24Pd(SC8H9)18, as compared to Au25(SC8H9)18. The results indicate that Pd-substitution for Au in Au25(SC8H9)18 results in increased angular momenta for metal-metal intraband transitions; the Landé g-factor for these transitions increased by ≈55% upon substitution, as compared to an approximate 19% increase for ligand-based transitions. The increased angular momentum translates to a 30% increase in electron-phonon coupling constants for intraband transitions, but only a 3% increase for ligand-based transitions. As a result, Pd substitution leads to less efficient metal-metal (intraband) radiative emission for Au24Pd (SC8H9)18 than for Au25(SC8H9)18.
AB - The photoluminescence (PL) of Au25(SC8H9)18 and Au24Pd(SC8H9)18 was investigated using variable-field magnetic circular photoluminescence (VH-MCPL) spectroscopy. The comparison of low-temperature (4.5 K) PL spectra measured for both nanoclusters revealed an ≈40 meV blueshift of intraband emission upon Pd substitution. Compared to that for the the Au25(SC8H9)18 cluster, the degree of circular-polarization for the Au24Pd(SC8H9)18 cluster increased for the low energy (<1.65 eV) portion of the PL spectrum, but decreased for the higher energy (>1.65 eV) spectral region. MCPL spectra included three distinct components, underlying the global PL spectrum, for both clusters. Variable-field analysis of each MCPL component revealed an increase in spin-orbit coupling (Landé g-factor) magnitudes for radiative transitions of the Pd-substituted cluster with respect to Au25(SC8H9)18. Variable-temperature (VT) PL spectroscopy yielded reduced integrated global PL intensity and increased electron-vibrational coupling for Au24Pd(SC8H9)18, as compared to Au25(SC8H9)18. The results indicate that Pd-substitution for Au in Au25(SC8H9)18 results in increased angular momenta for metal-metal intraband transitions; the Landé g-factor for these transitions increased by ≈55% upon substitution, as compared to an approximate 19% increase for ligand-based transitions. The increased angular momentum translates to a 30% increase in electron-phonon coupling constants for intraband transitions, but only a 3% increase for ligand-based transitions. As a result, Pd substitution leads to less efficient metal-metal (intraband) radiative emission for Au24Pd (SC8H9)18 than for Au25(SC8H9)18.
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U2 - 10.1021/acs.jpcc.1c00799
DO - 10.1021/acs.jpcc.1c00799
M3 - Article
AN - SCOPUS:85104950955
SN - 1932-7447
VL - 125
SP - 7267
EP - 7275
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 13
ER -