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In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, k, by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal…

While mid-infrared radiation can be used to identify and quantify numerous chemical species, contemporary broadband mid-IR spectroscopic systems are often hindered by large footprints, moving parts and high power consumption. In this work,…

Millimeter-wave massive multiple-input multiple-output systems employ highly directional beamforming to overcome severe path loss, and their performance critically depends on accurate beam alignment. Conventional codebook-based methods…

Signal Processing · Electrical Eng. & Systems 2026-02-26 Weijie Jin , Jing Zhang , Hengtao He , Chao-Kai Wen , Xiao Li , Shi Jin

The mathematical theory of compressed sensing (CS) asserts that one can acquire signals from measurements whose rate is much lower than the total bandwidth. Whereas the CS theory is now well developed, challenges concerning hardware…

Scanning nanobeam electron diffraction (NBED) with fast pixelated detectors is a valuable technique for rapid, spatially resolved mapping of lattice structure over a wide range of length scales. However, intensity variations caused by…

Frequency domain spectroscopy allows an experimenter to establish optical properties of solids in a wide frequency band including the technically challenging 10 THz region, and in other bands enables metrological comparison between…

Optics · Physics 2018-09-21 Steven Chick , Ben Murdin , Guy Matmon , Mira Naftaly

The enhancement of spectrum efficiency and the realization of secure spectrum utilization are critically dependent on spectrum cognition. However, existing spectrum cognition methods often exhibit limited generalization and suboptimal…

Signal Processing · Electrical Eng. & Systems 2025-08-12 Chunyu Liu , Hao Zhang , Wei Wu , Fuhui Zhou , Qihui Wu , Derrick Wing Kwan Ng , Chan-Byoung Chae

Transition Edge Sensor (TES) spectrometers for hard X-ray beamline science will enable improved X-ray emission and absorption spectroscopy in the information-rich 2 to 20 keV energy range. We are building a TES-based instrument for the…

Instrumentation and Detectors · Physics 2020-08-26 Tejas Guruswamy , Lisa M. Gades , Antonino Miceli , Umeshkumar M. Patel , John T. Weizeorick , Orlando Quaranta

High-resolution gas phase spectroscopy techniques in the microwave, millimeter-wave and terahertz spectral ranges can be used to study complex organic molecules desorbed from interstellar ice analogues surface with a high sensitivity.…

Instrumentation and Methods for Astrophysics · Physics 2019-12-23 Patrice Theulé , Christian Endres , Marius Hermanns , Jean-Baptiste Bossa , Alexey Potapov

The optical absorption spectrum of the three most stable isomers of the Ag11 system was calculated using the time-dependent density functional theory, with the generalized gradient approximation for the exchange and correlation potential,…

Atomic and Molecular Clusters · Physics 2009-11-13 Jose I. Martinez , Eva M. Fernandez

Multi-spectral imaging, which simultaneously captures the spatial and spectral information of a scene, is widely used across diverse fields, including remote sensing, biomedical imaging, and agricultural monitoring. Here, we introduce a…

A new technical method is developed for soft x-ray spectroscopy of near-edge x-ray absorption fine structure (NEXAFS). The measurement is performed with continuously rotating linearly polarized light over 2$\pi$, generated by a segmented…

Instrumentation and Detectors · Physics 2021-11-10 Yoshiki Kudo , Yasuyuki Hirata , Masafumi Horio , Masahito Niibe , Iwao Matsuda

The absorption and emission spectrum arising from the vibrational motion of a molecule is mostly in the infrared region. These fingerprint absorptions of polar bonds enable us to acquire bond-specific chemical information from specimens.…

Optics · Physics 2024-11-15 Govind Dayal , Dheeraj Pratap

Positron annihilation spectroscopy is often used to analyze the local electronic structure of materials of technological interest. Reliable theoretical tools are crucial to interpret the measured spectra. Here, we propose a parameter-free…

Materials Science · Physics 2015-04-15 Bernardo Barbiellini , Jan Kuriplach

A femtosecond mode-locked laser is used for the first time as a broadband infrared source for high resolution Fourier transform absorption spectroscopy. Demontration is made with a Cr^4+:YAG laser. The entire nu_1+nu_3 vibration-rotation…

Conventional colorimetric sensing methods typically rely on signal intensity at a single wavelength, often selected heuristically based on peak visual modulation. This approach overlooks the structured information embedded in full-spectrum…

Medical Physics · Physics 2026-04-16 Majid Aalizadeh , Chinmay Raut , Ali Tabartehfarahani , Xudong Fan

This paper proposes a novel and rapid calibration-free wavelength modulation spectroscopy algorithm based on even-order harmonics. The proposed algorithm, analytically deduced from Voigt line-shape function, only involves simple algebraic…

Optics · Physics 2021-09-01 Yihong Wang , Bin Zhou , Chang Liu

We address the question of the optimal broadband absorption of waves in an open, dissipative system. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasi-normal modes and radiative and…

Optics · Physics 2024-07-30 Stéphane Collin , Maxime Giteau

Linear and non-linear spectroscopies are powerful tools used to investigate the energetics and dynamics of electronic excited states of both molecules and crystals. While highly accurate \emph{ab initio} calculations of molecular spectra…

Materials Science · Physics 2019-09-26 Alan M. Lewis , Timothy C. Berkelbach

Collinear laser spectroscopy has been performed on He-like C$^{4+}$ ions extracted from an electron beam ion source (EBIS). In order to determine the transition frequency with the highest-possible accuracy, the lineshape of the fluorescence…

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