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1. Electronic relaxation dynamics in [Au ₂₅ (SR) ₁₈ ] ⁻¹ (R = CH ₃ , C ₂ H ₅ , C ₃ H ₇ , MPA, PET) thiolate-protected nanoclusters

   https://doi.org/10.1039/C9CP04039K  

   Senanayake, Ravithree D. ; Aikens, Christine M. ( March 2020 , Physical Chemistry Chemical Physics)

   We investigate the excited electron dynamics in [Au 25 (SR) 18 ] −1 (R = CH 3 , C 2 H 5 , C 3 H 7 , MPA, PET) [MPA = mercaptopropanoic acid, PET = phenylethylthiol] nanoparticles to understand how different ligands affect the excited state dynamics in this system. The population dynamics of the core and higher excited states lying in the energy range 0.00–2.20 eV are studied using a surface hopping method with decoherence correction in a real-time DFT approach. All of the ligated clusters follow a similar trend in decay for the core states (S 1 –S 6 ). The observed time constants are on the picosecond time scale (2–19 ps), which agrees with the experimental time scale, and this study confirms that the time constants observed experimentally could originate from core-to-core transitions and not from core-to-semiring transitions. In the presence of higher excited states, R = H, CH 3 , C 2 H 5 , C 3 H 7 , and PET demonstrate similar relaxations trends whereas R = MPA shows slightly different relaxation of the core states due to a smaller gap between the LUMO+1 and LUMO+2 gap in its electronic structure. The Smore »1 (HOMO → LUMO) state gives the slowest decay in all ligated clusters, while S 7 has a relatively long decay. Furthermore, separate electron and hole relaxations were performed on the [Au 25 (SCH 3 ) 18 ] −1 nanocluster to understand how independent electron and hole relaxations contribute to the overall relaxation dynamics.« less
2. Nonradiative relaxation dynamics in the [Au _25-n Ag _n (SH) ₁₈ ] ⁻¹ ( n = 1, 12, 25) thiolate-protected nanoclusters

   https://doi.org/10.1063/5.0045590  

   Pandeya, Pratima ; Senanayake, Ravithree D. ; Aikens, Christine M. ( May 2021 , The Journal of Chemical Physics)
3. Theoretical Investigation of Relaxation Dynamics in Au ₃₈ (SH) ₂₄ Thiolate-Protected Gold Nanoclusters

   https://doi.org/10.1021/acs.jpcc.8b03595  

   Senanayake, Ravithree D. ; Guidez, Emilie B. ; Neukirch, Amanda J. ; Prezhdo, Oleg V. ; Aikens, Christine M. ( July 2018 , The Journal of Physical Chemistry C)
4. Au _130−x Ag _x Nanoclusters with Non‐Metallicity: A Drum of Silver‐Rich Sites Enclosed in a Marks‐Decahedral Cage of Gold‐Rich Sites

   https://doi.org/10.1002/anie.201908694  

   Higaki, Tatsuya ; Liu, Chong ; Morris, David J. ; He, Guiying ; Luo, Tian‐Yi ; Sfeir, Matthew Y. ; Zhang, Peng ; Rosi, Nathaniel L. ; Jin, Rongchao ( December 2019 , Angewandte Chemie International Edition)
5. Controlling magnetism of Au ₁₃₃ (TBBT) ₅₂ nanoclusters at single electron level and implication for nonmetal to metal transition

   https://doi.org/10.1039/c9sc02736j  

   Zeng, Chenjie ; Weitz, Andrew ; Withers, Gayathri ; Higaki, Tatsuya ; Zhao, Shuo ; Chen, Yuxiang ; Gil, Roberto R. ; Hendrich, Michael ; Jin, Rongchao ( October 2019 , Chemical Science)

   The transition from the discrete, excitonic state to the continuous, metallic state in thiolate-protected gold nanoclusters is of fundamental interest and has attracted significant efforts in recent research. Compared with optical and electronic transition behavior, the transition in magnetism from the atomic gold paramagnetism (Au 6s 1 ) to the band behavior is less studied. In this work, the magnetic properties of 1.7 nm [Au 133 (TBBT) 52 ] 0 nanoclusters (where TBBT = 4- tert -butylbenzenethiolate) with 81 nominal “valence electrons” are investigated by electron paramagnetic resonance (EPR) spectroscopy. Quantitative EPR analysis shows that each cluster possesses one unpaired electron (spin), indicating that the electrons fill into discrete orbitals instead of a continuous band, for that one electron in the band would give a much smaller magnetic moment. Therefore, [Au 133 (TBBT) 52 ] 0 possesses a nonmetallic electronic structure. Furthermore, we demonstrate that the unpaired spin can be removed by oxidizing [Au 133 (TBBT) 52 ] 0 to [Au 133 (TBBT) 52 ] + and the nanocluster transforms from paramagnetism to diamagnetism accordingly. The UV-vis absorption spectra remain the same in the process of single-electron loss or addition. Nuclear magnetic resonance (NMR) is applied to probe the chargemore »and magnetic states of Au 133 (TBBT) 52 , and the chemical shifts of 52 surface TBBT ligands are found to be affected by the spin in the gold core. The NMR spectrum of Au 133 (TBBT) 52 shows a 13-fold splitting with 4-fold degeneracy of 52 TBBT ligands, which are correlated to the quasi- D 2 symmetry of the ligand shell. Overall, this work provides important insights into the electronic structure of Au 133 (TBBT) 52 by combining EPR, optical and NMR studies, which will pave the way for further understanding of the transition behavior in metal nanoclusters.« less