Letter: The Formation of Ion Packages with Ultrashort Duration in a Laser Ion Source

Abstract

A new approach to the formation of ultrashort laser ion packages in the ion source of time-of-flight (TOF) mass spectrometer for elemental analysis is described. This is achieved by installing a wedge-shaped reflector with special correcting plates. The reflector provides time and space focusing of the ion packages. Such time focusing allows to reduce the ion package duration up to 1 ns. The proposed approach allows more than order of magnitude increase in the resolution of the laser TOF mass spectrometer with an axially symmetric electrostatic analyzer to 10,000-13,000. In this Letter the theoretical calculations justifying the proposed method are presented.

Compact Analyzer for a Laser Time-of-Flight Mass Spectrometer

“…Three uses of wedge-shaped mirrors have been discovered during the development of this idea: 1) as a part of the ion source, 10 2) as an ion analyzer (this letter), and 3) as a combination of an ion source and an analyzer (a promising research direction). The first use allows the ultra-short ion packets to be formed in a laser ion source.…”

“…This provides the time focusing of ions of the third order, which reduces the time aberration by energy down to 1 ns. 10 In the second use, the wedge shape of the mirror provides time focusing by energy and with an additional single ion lens it also provides time focusing by the divergence angles of ions.…”

“…Previously, 10 it has been shown that during sample evaporation and laser plasma generation, a package of ions of 1-2 ns duration is formed. The ions acquire a large energy spread ~40-300 eV.…”

“…This direction is also promising for mass spectrometers with laser ion sources. [9][10][11] Currently, mass spectrometers are unpopular in elemental analysis for process control, compared to spectrometers. The reason is their high cost.…”

A Method for the Chromatic Aberration Correction of a Laser Time of-Flight Mass Analyzer

“…1 In the case of solid analyses, the laser TOF mass spectrometers is a promising instrument to use. In Sysoev et al, 2 it was proposed to increase the resolution by the use of a wedge-shaped reflector in combination with an axially symmetric electrostatic analyzer, which improves the resolution up to 10,000-13,000. The usage of such reflectors could be a step forward in solving the problem of decreasing the weight, size, and cost parameters of TOF mass spectrometers.…”