High resolution terahertz spectroscopy for analytical applications

Abstract

The latest achievements in the area of terahertz spectrometers based on transient effects are presented. The potential to use these spectrometers in various applications demanding the composition analysis of multicomponent gas mixtures simultaneously with a high sensitivity (at the ppb level) and resolving power is considered. The results obtained with the use of transient terahertz spectroscopy for medical diagnostics, security systems, etc. are shown.

Analysis of the Thermal Decomposition Products of Pathological and Healthy Tissues in Paranasal Sinuses: A High-Resolution Terahertz Gas Spectroscopy Study

“…This is done by periodically switching the phase or frequency of the probe radiation resonantly interacting with the medium, which leads to non-stationary radiation and absorption, i.e., to the periodic appearance and decay of induced macroscopic polarization. For this we have developed a spectrometer with phase switching of radiation and a fast frequency sweep spectrometer [10]. The phase switching mode [13] allows measurements to be performed at a particular frequency and is needed to monitor the dynamics of the selected substance concentration.…”

“…The molecular absorption spectroscopy, in particular spectroscopy based on nonstationary effects (the appearance and decomposition of macroscopic polarization) is an effective approach to the study of multicomponent gas mixtures. Non-stationary spectrometers have the best approximation to the theoretical sensitivity limit (the sensitivity for some gases is about 0.2 ppb in the scanning mode with a significant decrease in gas pressure (down to hundredths and thousandths of a torr)) with a resolution limited only by the Doppler effect [10]. The use of the terahertz (THz) frequency range, where the most intense absorption lines of the rotational spectrum of molecules, including organic ones, lie, makes this approach convenient for studying multicomponent gas mixtures of different origins, including biological ones [11,12].…”

Terahertz high-resolution spectroscopy of thermal decomposition gas products of diabetic and non-diabetic blood plasma and kidney tissue pellets

“…In addition, it enables determining the component composition of a gas mixture with high reliability. 12 …”

“…The molecular absorption spectroscopy and in particular THz gas spectroscopy is a very promising approach for investigations of multicomponent gas mixtures of various origins. 12 The samples in liquid and solid state can be investigated by vaporing or thermal decomposition. The metabolites-markers of socially important diseases (diabetes, cancer, etc.)…”

The Effect of Layer-by-Layer Building in Selective Laser Sintering on the Performance of Polymer-Based THz Optical Systems

“…With the advent of more powerful THz radiation sources, such as those based on fs-laser, THz quantum cascade lasers, THz parametric oscillators, free electron lasers in addition to more performant detectors, the THz spectral domain has become a field of maximum interest for many imaging applications such as medicine [1][2][3][4][5], atom probe tomography [6], spectroscopy [7][8][9], astronomy [10][11][12], defense and security [13][14][15], quality control [16][17][18] to name only a few.…”