研究開発ジャーナル
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概要

EUV laser mass spectrometry and photoelectron spectroscopy of mass selected neutral clusters and molecules.

Elliot R Bernstein

A long standing set of goals for studies of systems of inhomogeneous, neutral clusters (e.g., MmXn or (molecule)p) has been to mass sort and select them individually for determination of physical and chemical properties of each neutral cluster by spectroscopic techniques. We have constructed appropriate instrumentation to achieve these important goals employing photoelectron spectroscopy (PES), driven by both visible (for MmXn-) and EUV (for MmXn0) radiation. Our 26.5 eV/photon EUV laser can ionize any neutral cluster or molecule (EUV PES) that can be identified and isolated. The algorithm includes the following steps: 1. generation of cluster negative ions in a laser ablation supersonic source with the addition, as required, of low energy electrons from a Y2O3 disk; 2. separation of these anionic clusters in a reflectron time of flight mass spectrometer (RTOFMS); 3.selection and slowing of specific, chosen clusters in a mass gate/momentum deceleration stage; 4.threshold photo-detachment of the sorted and selected negative ion clusters with a tunable VIS/UV laser to generate neutral, isolated clusters; and 5. EUV PES of these neutral clusters. Such studies generate vibrational and structural information on the ground states of the neutral clusters (through VIS/UV PES), and information on the ion states of the clusters (through EUV PES).