TY - JOUR
T1 - Size-Scalable Near-Infrared Photoluminescence in Gold Monolayer Protected Clusters
AU - Herbert, Patrick J.
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 Grants 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 Grants CHE-1905179 and CHE-1507646.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/8/12
Y1 - 2021/8/12
N2 - Near-infrared photoluminescence of a series of three gold monolayer protected clusters (MPCs) with volumes spanning 50-200 Å3 was studied by using variable-temperature photoluminescence (VT-PL) spectroscopy. The three MPCs, which included Au20(SC8H9)15-diglyme, Au25(SC8H9)18, and Au38(SC12H25)24, all exhibited temperature-dependent intensities that reflected a few-millielectronvolt energy gap that separated bright emissive and dark nonradiative electronic states. All clusters showed increased PL intensities upon raising the sample temperature from 4.5 K to a cluster-specific value, upon which increased sample temperature resulted in emission quenching. The increased PL in the low-temperature range is attributed to thermally activated carrier transfer from dark to bright states. The quenching at elevated temperatures is attributed to nonradiative vibrational relaxation through Au-Au stretching of the MPCs metal core. Importantly, the results show evidence of a common and size scalable metal-centered intraband PL mechanism that is general for ultrasmall metal nanoclusters, which are expected to show nonscalable optical properties.
AB - Near-infrared photoluminescence of a series of three gold monolayer protected clusters (MPCs) with volumes spanning 50-200 Å3 was studied by using variable-temperature photoluminescence (VT-PL) spectroscopy. The three MPCs, which included Au20(SC8H9)15-diglyme, Au25(SC8H9)18, and Au38(SC12H25)24, all exhibited temperature-dependent intensities that reflected a few-millielectronvolt energy gap that separated bright emissive and dark nonradiative electronic states. All clusters showed increased PL intensities upon raising the sample temperature from 4.5 K to a cluster-specific value, upon which increased sample temperature resulted in emission quenching. The increased PL in the low-temperature range is attributed to thermally activated carrier transfer from dark to bright states. The quenching at elevated temperatures is attributed to nonradiative vibrational relaxation through Au-Au stretching of the MPCs metal core. Importantly, the results show evidence of a common and size scalable metal-centered intraband PL mechanism that is general for ultrasmall metal nanoclusters, which are expected to show nonscalable optical properties.
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U2 - 10.1021/acs.jpclett.1c02100
DO - 10.1021/acs.jpclett.1c02100
M3 - Article
C2 - 34347490
AN - SCOPUS:85113596534
SN - 1948-7185
VL - 12
SP - 7531
EP - 7536
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 31
ER -