Far‐Ultraviolet ( FUV ) Spectroscopy in the Solid and Liquid States, Principle, Instrumentation, and Application of

Abstract

This article outlines recent progress in ultraviolet (UV) spectroscopy in the 140–280 nm region of solid and liquid phases. In this article, we refer to the 120–200 nm region as the far‐UV (FUV) region. The word ‘vacuum UV region’ is not appropriate any more at least for the 120–200 nm region because most of recent spectrometers used in this region do not have the vacuum evaporation system but have the nitrogen gas purged system. FUV spectroscopy is concerned with electronic transitions of a molecule, but the absorptivity is very high in the FUV region, and, therefore, this region has been employed to investigate mainly for the electronic states and structure of gas molecules. To observe spectra of solid samples in the FUV region, reflection spectroscopy has been used. However, for liquid samples, in general, it is very difficult to use either absorption spectroscopy or reflection spectroscopy. Accordingly, FUV spectroscopy for liquid samples has almost been an undeveloped research area. To solve these difficulties in FUV spectroscopy we have recently developed a totally new FUV spectrometer based on the attenuated total reflection (ATR) technique that enables us to measure spectra of liquid and solid samples in the 140–280 nm region. This spectrometer has opened up a new era of FUV spectroscopy. This article consists of seven parts: (i) introduction to FUV spectroscopy, (ii) characteristics and advantages of FUV spectroscopy for the study of liquids and solids, (iii) development of new FUV spectrometers, (iv) FUV studies of liquid water and aqueous solutions, (v) FUV spectra of organic molecules in the liquid states, (vi) potential applications of FUV spectroscopy in liquid and solid states, and (vii) time‐resolved (TR) FUV spectroscopy. This article demonstrates that FUV holds considerable promise not only in basic science but also in applications such as qualitative and quantitative analyses, on‐line monitoring, environmental geochemical analysis, and surface analysis.

Construction of a vacuum ultraviolet transmission spectrometer

“…VUV spectral region covers wavelengths which are of interest for two main research applications: (i) development of UV optics for excimer lasers and photolithography [7,8], (ii) material science (diamond, polymer thin films) [4][5][6]. Construction of a transmission spectrometer in this spectral range is indispensable for carrying out the research in the two topical directions.…”

“…A number of spectral features of interest are present in the ultraviolet (UV) part of spectra or even in the so-called vacuum UV (VUV) region with wavelengths below 190 nm [4][5][6]. This term is used due to the necessity to carry out the measurements in vacuum, since air very strongly absorbs the light in this spectral region.…”

Comparative Investigation of the Spectroscopic Behavior Based on High-Concentrated Solution in Nitrogen and Air Atmospheres

“…also faces interference caused by ultraviolet attenuation. Specifically, UV light with a wavelength lower than 240 nm is easily absorbed by oxygen in the air along the optical transmission path, resulting in attenuation of light intensity that is not attributable to the sample absorption [ 33 , 34 ]. Wang et al pointed out the extent of the absorption of ultraviolet light by different concentrations of oxygen in the environment [ 35 ].…”