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Mid-IR is considered a molecular fingerprint region that is particularly suitable for sensitive chemical detection in the atmosphere. In the recent years quantum cascade lasers (QCLs) and interband cascade lasers (ICLs) become semiconductor sources of choice for high resolution spectrometry in the mid-IR. An ideal spectroscopic system should provide simultaneous spectroscopic detection of large molecules...
Ethylene (C2H4) is known to be a plant hormone significantly affecting the growth, ripening, and decay of fruits [1], an important biomarker reflecting people's health condition [2], and a primary pollutant in promoting the formation of tropospheric ozone in urban areas [3]. The detection of C2H4 at parts per billion (ppb) — parts per million (ppm) concentration levels is crucial in numerous applications...
Hybrid quantum systems are promising candidates for realizing a quantum network. A particularly interesting approach in this context relies on optical-nanofiber-based atom-photon interfaces [1]. Using a two-color evanescent field, cold neutral atoms are trapped about 200nm away from the nanofiber surface. This small distance allows evanescent coupling between the trapped atoms and additional fiber-guided...
Active optical sensing of the atmosphere through long distances from airborne or satellite platforms requires specific and demanding features for the necessary laser sources in terms of wavelength addressing and power level. Many molecules of atmospheric interest for nowadays urgent issues like climate change and contrails (CO2, CH4, H2O) have their best relevant detection features in the near and...
Quartz-enhanced photoacoustic spectroscopy (QEPAS) is an alternative approach to photoacoustic detection of trace gas, exploiting the enhancement of acoustic energy density provided by a quartz tuning fork (QTF), which acts as a high quality factor piezoelectric acoustic transducer and allowing the use of extremely small volumes [1]. We will report on the latest advances and new developments of QEPAS...
To help consumers enjoy healthy food, technology investigation for food freshness sensing are conducted. In this study meat is selected as the detection target based on a consumer survey. Near infrared spectroscopy, pH, CO2, TVOC, and auto fluorescence are investigated. The results showed that CO2 and TVOC could be a used for meat freshness sensing in a closed space such as box. Near infrared spectroscopy...
Terahertz (THz) spectroscopy is a promising way to measure the spectrum of low-frequency modes of molecules or ensembles, such as crystals and polymers, including proteins. However, the main drawback of THz spectroscopy is its extremely low sensitivity. In the present study, we report on signal enhancement in THz spectroscopy achieved by depositing a mino acid molecules or their derivatives on a gold...
Tip-enhanced optical spectroscopy (TERS) has been nowadays recognized as a powerful tool for nano-imaging and nano-analysis with a nanoscale spatial resolution far beyond the diffraction limit of light. A metallic probe tip plays important roles in confining and enhancing the incident light field due to the excitation of localized modes of surface plasmon polaritons at the nanoscale tip-apex. When...
Charged water interfaces are ubiquitous and responsible for many important processes in nature and modern technologies, such as protein folding, electrochemistry, and photocatalysis. They appear in the form of an electric double layer that can be divided into two sub-layers. One is the so-called Stern layer composed of one to two hardly mobile, hydrogen-bonded, water monolayers next to the charged...
The hydroxyl (OH) radical plays a critical role in atmospheric chemistry due to its high reactivity with volatile organic compounds (VOCs) and other trace gaseous species. Because of its very short life time and very low concentration in the atmosphere, interference-free high sensitivity in-situ OH monitoring by laser spectroscopy represents a real challenge. We report on the development of a Faraday...
Time-domain terahertz spectroscopy (THs-TDS) has demonstrated its power in last two decades. With technological development of ultra-fast lasers and THz photonics, the sensitivity, signal dynamic range and the speed of acquisition of spectral information have been continuously improved. Here we present a proof of the principle of a confluence of THz-TDS and quantum cascade laser that holds promise...
This presentation will focus on recent advances in spectrophone designs based on quartz-enhanced photoacoustic spectroscopy (QEPAS) and quartz-enhanced conductance spectroscopy (QECS) for highly selective and sensitive monitoring as well as quantification of trace gas species and nanomechanical analysis of materials [1–4]. QEPAS sensor technology is based on a new approach to photoacoustic detection...
There has been a recent growth of activity in nonlinear time domain terahertz spectroscopy because of the development of a number of intense lab based sources and ultra-broadband detection schemes. Much of the interest stems from the possibility of exploring new physics by driving condensed matter far from equilibrium with THz fields in the 0.1 to 10MV/cm range [1]. The variety of different approaches...
Gas barrier films are conventionally used as in order to protect the liquid crystal devices and foods against such as water vapor and oxygen gas. A performance of gas barrier film largely depends on water molecules in the films, since the water molecules in the films generally interact with the atoms of films and change the diffusion speeds of the gases in the films. However, the relation between...
In China, particulate pollution is a serious environment problem that is influencing air quality, regional and global climates, and human health. Emission of gaseous ammonia has long been known to play an important role in the air pollutants because of its contribution to secondary aerosol formation which is the major component of PM2.5 (particulate matter with an aerodynamic diameter less than 2...
We review the recent progress on Inhibited-Coupling (IC) guiding hollow-core photonic crystal fibers (HC-PCF) and their applications in atom optics. We start with describing the new development in IC guiding HC-PCF, which led to a new transmission performance state-of-the-art. We then review the different results obtained in thermal rubidium filled HC-PCF such as the effect of the fiber core wall...
The authors discuss the principle of physical similitude to obtain models suitable for the analysis and description of signal measurement tasks, whose character is evaluated quantitatively. In this context, the paper presents a simple example of using a broadband noise signal to investigate periodic structures, and it also characterizes the basic tests related to the described problem. The tested...
In the past few years, a new phenomenon of absorption, called “coherent perfect absorption (CPA)”, has attracted significant attentions [1, 2]. CPA relies on the coherent interference of light. In a typical CPA system, two coherent beams are incident on the absorber from opposite sides and the reflected light of one beam interfere with the transmitted light of the other and vice versa. CPA was first...
Ultrashort pulse (USP) fiber lasers have become one of the most important instruments in various fields of science and industry during two past decades [1]. A number of applications requires stability of pulse duration, repetition rate and low intensity noise of an USP source. For example, stabilization of this parameters is in great demand in frequency metrology field, dual comb spectroscopy, THz...
A compact nitrogen dioxide (NO2) detection system is developed based on differential optical absorption spectroscopy (DOAS) using light emitting diode (LED) as the light source. Alumina ceramic, with properties of highly scattering and low absorption in the wavelength region of 430 ∼ 450 nm, is utilized as the gas cell to make the system extremely compact. Nitrogen dioxides with various concentrations...
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