Sub-picosecond photodynamics of small neutral copper oxide clusters
The ultrafast dynamics of neutral copper oxide clusters (Cu n O x , n < 5) are reported using femtosecond pump probe spectroscopy in the gas phase. The transient spectra recorded for each cluster demonstrate they relax on a 100s of fs timescale followed by a long-lived (>50 ps) response. Densi...
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Veröffentlicht in: | Physical chemistry chemical physics : PCCP 2024-08, Vol.26 (31), p.2937-2946 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The ultrafast dynamics of neutral copper oxide clusters (Cu
n
O
x
,
n
< 5) are reported using femtosecond pump probe spectroscopy in the gas phase. The transient spectra recorded for each cluster demonstrate they relax on a 100s of fs timescale followed by a long-lived (>50 ps) response. Density functional theory calculations are performed to determine the lowest energy structures and spin states. Topological descripters for the excited states are calculated (time-dependent density functional theory) to relate the measured excited state dynamics to changes in the cluster's electronic structure with increasing oxidation. Strong field ionization is demonstrated here to be a soft form of ionization and able to record transient signals for clusters previously determined to be unstable to nanosecond multiphoton ionization. The relative cluster stability is further demonstrated by signal enhancement/depreciation that is recorded through the synergy from the two laser pulses. Once the oxygen atoms exceed the number of copper atoms, a weakly bound superoxide O
2
unit forms, exhibiting a higher spin state. All clusters that are not in the lowest spin configuration demonstrate fragmentation.
The excited state lifetimes of small neutral copper oxide clusters decrease with oxidation on the sub-picosecond timescale. |
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ISSN: | 1463-9076 1463-9084 1463-9084 |
DOI: | 10.1039/d4cp01544d |