Poster Presentations
Day 2, June 11（Thu.） Room P (5F 501+502)
- 2P-30
Study of Non-equilibrium Ion Emission in Single-pulse Femtosecond Laser Desorption by Time-of-Flight Mass Spectrometry
(1UOsaka, 2Ind. Sch., 3Kyoto Univ.)
oJianzhong Wang1, Yasuo Kanematsu1, Atsushi Muratsugu2, Fuyuki Matsuda3, Wakana Matsuda1, Yosuke Kawai1, Michisato Toyoda1
Femtosecond (fs) laser desorption/ionization reduces thermal diffusion and collateral damage and enables high-spatial-resolution mass spectrometry. Ultrafast laser–matter interaction can trigger non-equilibrium desorption, often discussed in terms of electrostatic ablation and Coulomb explosion, and the relative contribution of these processes is highly sensitive to laser fluence and pulse duration. However, ion energy distributions produced by a single fs-laser pulse are rarely measured directly. Here we record one time-of-flight (TOF) spectrum for every fs-laser pulse, so that each pulse is treated as an independent ion-emission event. Each single-pulse TOF spectrum is converted to an initial kinetic-energy spectrum, from which we extract three intuitive quantities: the ion yield N (the total number of detected ions), the mean ion kinetic energy ⟨E⟩ (the average energy of those ions), and the energy spread σE (how broad the energy distribution is, used as an effective ion temperature). Using CsI deposits, we acquired 2000 single-pulse spectra at 800 nJ for pulse durations of 180, 660, and 1500 fs. The shortest pulse (180 fs) shows higher ⟨E⟩ and larger σE than longer pulses, indicating stronger nonthermal ion emission, whereas 660–1500 fs results are more consistent with thermal ion emission.