Development of a portable time-of-flight mass spectrometer prototype using a cold electron source

Wanseop Jeong; Hyun Sik Kim; Byeongwon Kang

doi:10.1063/5.0074883

Development of a portable time-of-flight mass spectrometer prototype using a cold electron source

Rev Sci Instrum. 2022 Feb 1;93(2):023302. doi: 10.1063/5.0074883.

Authors

Wanseop Jeong¹, Hyun Sik Kim², Byeongwon Kang¹

Affiliations

¹ Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea.
² Mass Spectrometry and Advanced Instrumentation Group, Korea Basic Science Institute, Cheongju 28119, Republic of Korea.

PMID: 35232126
DOI: 10.1063/5.0074883

Abstract

Fundamental obstacles toward the development of a portable time-of-flight mass spectrometer (TOF MS) are ionization sources and vacuum systems. To overcome these, a cold electron source (CES) and a pulse valve are introduced in this study to examine the possibility of developing a portable TOF MS. The CES is developed using a microchannel plate electron multiplier radiated by ultraviolet photons from a light-emitting diode. The CES is controlled using short pulses to generate accelerated electrons that ionize a substrate surface. A 10 ns CES pulse produces an electron flux density of 10¹³ to 10¹⁴ m^-2 on the surface, and the short pulse minimizes the ionization time such that the resolution limit associated with a short drift tube is overcome. In addition, the injected 0.05 m³ quantitative sample reduces the vacuum exhaust load, and simultaneously, it is possible to temporarily form layers of the target molecules on the substrate. The possibility of immediate measurement by directly injecting benzene at ambient pressure was verified through repeated measurements; therefore, it is technically possible to use a CES to allow for a highly compact (and portable) TOF MS.