2020/02/08 by A. Helal, Sandra Bruce, Helal, A. +6
Chemistry · Engineering · Physics and Astronomy · #Atomic and Molecular Clusters (physics.atm-clus) #FOS: Physical sciences #Laser-Matter Interactions and Applications #Laser-induced spectroscopy and plasma #Mass Spectrometry Techniques and Applications
paper · pdf · doi:10.48550/arxiv.2002.03070
openalex publication_date 2020/02/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We have studied the explosion dynamics of methane clusters irradiated by intense, femtosecond, 38 nm (32.6 eV) XUV laser pulses. The ion time-of-flight spectrum measured with a Wiley-McLaren-type time-of-flight spectrometer reveals undissociated molecular \textrmCH4+ ions, fragments which are missing hydrogen atoms due to the breakage of one or more C-H bonds (\textrmCH3+, \textrmCH2+ \textrmand \textrmCH+) and the recombination product \textrmCH5+. Also visible on the time-of-flight traces are atomic and molecular hydrogen ions (\textrmH+ \textrmand \textrmH2+), carbon ions, and larger hydrocarbons such as \textrmC2 \textrmH2+ and \textrmC2\textrmH3+. No doubly-charged parent ions (\textrmCH42+) were detected. The time-of-flight results show that total and relative ion yields depend strongly on cluster size. The absolute yields of \textrmCH+5 and \textrmH+ scale linearly with the yields of the other generated fragments up to a cluster size of ⟨\textrmN⟩=70,000 \textrmmolecules, then begin to decrease, whereas the yields of the \textrmCHn+(n=1-4) fragments plateau at this cluster size. The behavior of \textrmH+ may be understood through the electron recombination rate, which depends on the electron temperature and the cluster average charge. Moreover, the \textrmCH5+ behavior is explained by the depletion of both \textrmCH4+ and \textrmH+ via electron-ion recombination in the expanding nanoplasma.