The Absorption Behavior of Water and Some Organic Liquids in the Near Infrared Studied by Photoacoustic Spectroscopy

1984 ◽  
Vol 39 (12) ◽  
pp. 1242-1249 ◽  
Author(s):  
U. Haas ◽  
H. Seiler
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Near Infrared ◽  
Modulation Frequency ◽  
Incident Light ◽  
Photoacoustic Signal ◽  
Liquid Structure ◽  
Organic Liquids ◽  
Absorption Bands ◽  
Expected Frequency ◽  
Hydroxyl Absorption

The optical absorption of water and some organic liquids [CH3OH, CH3OD, CD3OD, C2H5OH, C4H9OH, (CH3)2CO, (C2H5)2O and C6H6] has been investigated in the near infrared by photoacoustic spectroscopy. Characteristical absorption bands of combinations and overtones of strong infrared fundamental vibrations are observed and can be used for qualitative analysis of these liquids. The amplitude of the photoacoustic signal shows an f-1-dependence of the modulation frequency f of the incident light for all absorption signals, except for the hydroxyl absorption bands of water and the alcohols. The deviation of the expected frequency dependence points to a modification of the liquid structure toward the surface of the liquid-gas boundary.

Trace gas detection based on photoacoustic spectroscopy in 3-D printed gas cell

2020 ◽  
Vol 28 (4) ◽  
pp. 236-242
Author(s):  
Shenlong Zha ◽  
Hongliang Ma ◽  
Changli Zha ◽  
Xueyuan Cai ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Near Infrared ◽  
Acoustic Pressure ◽  
Resonant Cavity ◽  
Photoacoustic Signal ◽  
Trace Gas ◽  
Integration Time ◽  
Photoacoustic Cell ◽  
Normal Atmospheric Pressure ◽  
Micro Resonator

A novel photoacoustic spectroscopy gas sensor based on a micro-resonator has been developed. The photoacoustic cell was designed and fabricated using 3-D printing and the photoacoustic cell volume was compressed significantly. This design greatly reduces the time of manufacturing the micro-resonator and the weight was lighter compared to traditional cells. Furthermore, the acoustic pressure distribution in the 3-D printed photoacoustic cell was analyzed by COMSOL Multiphysics software, which indicated that the strongest acoustic pressure occurred in the middle of the resonant cavity. The performance of the sensor was evaluated by detection of CH4 at normal atmospheric pressure used a near infrared distributed feedback laser emitted at 1653 nm. The characteristic of the photoacoustic signal under different pressures was also investigated. An Allan variance shows that the 3-D printed photoacoustic spectroscopy sensor has the detection limit of 1.44 ppmv (3σ) for CH4 detection at about 200 s integration time.

Fourier-transform photoacoustic spectroscopy: a more complete method for quantitative analysis

1986 ◽  
Vol 64 (9) ◽  
pp. 1081-1085 ◽  
Author(s):  
M. Choquet ◽  
G. Rousset ◽  
L. Bertrand
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
Quantitative Analysis ◽  
Photoacoustic Spectroscopy ◽  
Photoacoustic Signal ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Asbestos Fibers ◽  
Fourier Transform Spectra ◽  
Signal Saturation

Strong absorption bands of photoacoustic Fourier-transform spectra are often truncated relative to weaker bands owing to signal saturation. To correct this problem, we propose processing both the phase and the amplitude information in the photoacoustic signal. Under certain conditions, easily fulfilled in typical experiments, we are able to calculate the absolute absorption spectrum from the photoacoustic data. Experimental results are given for asbestos fibers (chrysotile).

scholarly journals Huge upconversion luminescence enhancement by a cascade optical field modulation strategy facilitating selective multispectral narrow-band near-infrared photodetection

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Yanan Ji ◽  
Wen Xu ◽  
Nan Ding ◽  
Haitao Yang ◽  
Hongwei Song ◽  
...  
Keyword(s):  
Near Infrared ◽  
Response Times ◽  
Modulation Frequency ◽  
Incident Light ◽  
Upconversion Luminescence ◽  
Optical Field ◽  
Lanthanide Ions ◽  
Hierarchical Architecture ◽  
Upconversion Nanocrystals ◽  
Field Modulation

Abstract Since selective detection of multiple narrow spectral bands in the near-infrared (NIR) region still poses a fundamental challenge, we have, in this work, developed NIR photodetectors (PDs) using photon upconversion nanocrystals (UCNCs) combined with perovskite films. To conquer the relatively high pumping threshold of UCNCs, we designed a novel cascade optical field modulation strategy to boost upconversion luminescence (UCL) by cascading the superlensing effect of dielectric microlens arrays and the plasmonic effect of gold nanorods, which readily leads to a UCL enhancement by more than four orders of magnitude under weak light irradiation. By accommodating multiple optically active lanthanide ions in a core-shell-shell hierarchical architecture, developed PDs on top of this structure can detect three well-separated narrow bands in the NIR region, i.e., those centered at 808, 980, and 1540 nm. Due to the large UCL enhancement, the obtained PDs demonstrate extremely high responsivities of 30.73, 23.15, and 12.20 A W−1 and detectivities of 5.36, 3.45, and 1.91 × 1011 Jones for 808, 980, and 1540 nm light detection, respectively, together with short response times in the range of 80–120 ms. Moreover, we demonstrate for the first time that the response to the excitation modulation frequency of a PD can be employed to discriminate the incident light wavelength. We believe that our work provides novel insight for developing NIR PDs and that it can spur the development of other applications using upconversion nanotechnology.

scholarly journals Photoacoustic Measurement of Ethane with Near-Infrared DFB Diode Laser

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Gang Cheng ◽  
Yuan Cao ◽  
Kun Liu ◽  
Gongdong Zhu ◽  
Guishi Wang ◽  
...  
Keyword(s):  
Diode Laser ◽  
Near Infrared ◽  
Second Harmonic ◽  
Modulation Frequency ◽  
Photoacoustic Signal ◽  
Minimum Detectable Concentration ◽  
Modulation Amplitude ◽  
Excitation Light ◽  
Detection Scheme ◽  
Detectable Concentration

A compact resonant photoacoustic sensor based on a near-infrared distributed-feedback (DFB) diode laser was developed for detection of ethane (C2H6). A DFB laser emission at 5937.25 cm−1 with a power of ∼5 mW was used as an excitation light source for generating the photoacoustic signal. Wavelength modulation and second harmonic detection scheme were employed. Modulation frequency and modulation amplitude were optimized for getting optimum performance. Performance evaluation based on the linearity response of the PAS sensor system with respect to C2H6 concentration levels was performed, and a good linear dependence of the PAS signal on the C2H6 concentration was obtained. A minimum detectable concentration of 9 ppmv was achieved for detection of C2H6 with a lock-in time constant of 10 ms.

Study of the liquid–gas boundary of water and alcohols by photoacoustic spectroscopy

1986 ◽  
Vol 64 (9) ◽  
pp. 1063-1066 ◽  
Author(s):  
U. Haas
Keyword(s):  
Heavy Water ◽  
Photoacoustic Spectroscopy ◽  
Structural Modification ◽  
Near Infrared ◽  
Modulation Frequency ◽  
Primary Alcohols ◽  
Hydrogen Bonded

Water, heavy water, and some primary alcohols (methanol, ethanol, propanol, and butanol) are investigated in the near infrared by photoacoustic (PA) spectroscopy. The PA amplitudes of "free" and hydrogen-bonded hydroxyl absorptions show a different dependence on modulation frequency f, deviating from an expected f−1 dependence for liquids. The investigations demonstrate that the liquids reveal a structural modification from the inside toward the liquid–gas boundary.

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

Structure and microstructure of near infrared-absorbing Au–Au2S nanoparticles

2007 ◽  
Vol 22 (9) ◽  
pp. 2531-2538 ◽  
Author(s):  
Mei Chee Tan ◽  
Jackie Y. Ying ◽  
Gan Moog Chow
Keyword(s):  
Optical Properties ◽  
Surface Segregation ◽  
Near Infrared ◽  
Small Degree ◽  
Core Shell ◽  
Shell Microstructure ◽  
Absorption Bands ◽  
Interfacial Effects ◽  
Nir Absorption ◽  
Structure And Microstructure

Near infrared (NIR) absorbing nanoparticles synthesized by the reduction of HAuCl4 with Na2S exhibited absorption bands at ∼530 nm, and in the NIR region of 650–1100 nm. The NIR optical properties were not found to be related to the earlier proposed Au2S–Au core-shell microstructure in previous studies. From a detailed study of the structure and microstructure of as-synthesized particles in this work, S-containing, Au-rich, multiply-twinned nanoparticles were found to exhibit NIR absorption. They consisted of amorphous AuxS (where x = 2), mostly well mixed within crystalline Au, with a small degree of surface segregation of S. Therefore, NIR absorption was likely due to interfacial effects on particle polarization from the introduction of AuxS into Au particles, and not the dielectric confinement of plasmons associated with a core-shell microstructure.

Composition, particle size, and near-infrared irradiation effects on optical properties of Au–Au2S nanoparticles

2008 ◽  
Vol 23 (1) ◽  
pp. 281-293 ◽  
Author(s):  
Mei Chee Tan ◽  
Jackie Y. Ying ◽  
Gan Moog Chow
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Thermal Effects ◽  
Near Infrared ◽  
Sodium Sulfide ◽  
Irradiation Effects ◽  
Absorption Bands ◽  
Molar Ratios ◽  
Nir Absorption ◽  
Structure And Microstructure

Near-infrared (NIR)-absorbing nanoparticles synthesized by the reduction of tetrachloroauric acid (HAuCl4) using sodium sulfide (Na2S) exhibited absorption bands at ∼530 nm and at the NIR region of 650−1100 nm. A detailed study on the structure and microstructure of as-synthesized nanoparticles was reported previously. The as-synthesized nanoparticles were found to consist of amorphous AuxS (x = ∼2), mostly well mixed within crystalline Au. In this work, the optical properties were tailored by varying the precursor molar ratios of HAuCl4 and Na2S. In addition, a detailed study of composition and particle-size effects on the optical properties was discussed. The change of polarizability by the introduction of S in the form of AuxS (x = ∼2) had a significant effect on NIR absorption. Also, it was found in this work that exposure of these particles to NIR irradiation using a Nd:YAG laser resulted in loss of the NIR absorption band. Thermal effects generated during NIR irradiation had led to microstructural changes that modified the optical properties of particles.

High-energy organic group-induced spectrally pure upconversion emission in novel zirconate-/hafnate-based nanocrystals

CrystEngComm ◽  
2015 ◽  
Vol 17 (37) ◽  
pp. 7169-7174 ◽  
Author(s):  
Xianghong He ◽  
Bing Yan
Keyword(s):  
Pump Power ◽  
Near Infrared ◽  
Incident Light ◽  
Upconversion Emission ◽  
High Energy ◽  
Single Band ◽  
Organic Group ◽  
Red Fluorescence

A series of novel fluoride-based nanophosphors (NPs) exhibiting spectrally pure upconversion (UC) red fluorescence upon near-infrared (980 nm) excitation. The single-band deep-red UC luminescence feature of K3MF7:Yb3+,Er3+ (M = Zr, Hf) NPs is independent of the doping levels of Yb3+–Er3+ and the pump power of incident light.

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