Showing papers on "Photoacoustic spectroscopy published in 1993"
TL;DR: A glucose concentration analysis of human whole blood samples has been accomplished using pulsed laser photoacoustic spectroscopy (LPAS) using a CO2 laser operating with μJ pulse energies to determine glucose concentrations within the physiological range.
Abstract: A glucose concentration analysis of human whole blood samples has been accomplished using pulsed laser photoacoustic spectroscopy (LPAS). Using a CO2 laser operating with microJ pulse energies, the technique has shown the required discrimination and sensitivity to determine glucose concentrations within the physiological range (18-450 mg dl-1) in whole blood samples. The sensitivity achieved with this system is comparable to that of the existing commercial enzyme-based diagnostic systems presently used in hospital clinical chemistry environments. The technique is compared with other optical methods that have recently been used for glucose determination, and its applicability for use in the development of an in vivo monitor is discussed.
111 citations
TL;DR: Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) is shown to be a useful tool for structural studies of hydrogen and/or oxygen chemisorption on the surface of diamond powders as mentioned in this paper.
Abstract: Fourier-transform infrared photoacoustic spectroscopy (FTIR-PAS) is shown to be a useful tool for structural studies of hydrogen and/or oxygen chemisorption on the surface of diamond powders. As compared with the diffuse reflectance method or the KBr pellet method, it has become clear that PAS has an advantage in terms of surface sensitivity. The possibility of quantitative analysis of chemisorbed hydrogen has also been demonstrated.
76 citations
TL;DR: A titanium:sapphire ring laser has been used in a high-resolution intracavity photoacoustic study of a natural sample of acetylene in the infrared region 11 480-11 880 cm−1.
41 citations
27 citations
TL;DR: Pulsed laser photoacoustic spectroscopy has been used as the basis for sensing analytes in aqueous systems as discussed by the authors, which gives this sensing technique advantages over conventional spectroscopic techniques in the potential application to water pollution monitoring and to measuring blood-glucose concentrations.
Abstract: Pulsed laser photoacoustic spectroscopy has been used as the basis for sensing analytes in aqueous systems. The spectra obtained with the photoacoustic system are significantly different from conventional transmission spectra and, in particular, the spectra of some organic solvents and alcohols show a marked enhancement in feature strength due to the dependence of physical and thermal factors in the photoacoustic generation process. The photoacoustic process has been shown to be almost immune to the effects of optical scattering, which gives this sensing technique advantages over conventional spectroscopic techniques in the potential application to water-pollution monitoring and to measuring blood-glucose concentrations.
27 citations
TL;DR: In this paper, a Fermi resonance model based on conventional rectilinear normal coordinate theory has been used to assign vibrationally bands from this work and from earlier studies.
Abstract: Intracavity photoacoustic overtone spectrum of monofluoroacetylene, HCCF, has been recorded in the wave number region 10 750–14 500 cm−1 with a titanium:sapphire ring laser. The spectrum contains many dense vibration–rotation band systems which can be resolved with Doppler limited resolution. Altogether 58 individual overtone bands have been analyzed rotationally. Many of the observed bands show perturbations of which some have been attributed to anharmonic resonance interactions. A Fermi resonance model based on conventional rectilinear normal coordinate theory has been used to assign vibrationally bands from this work and from earlier studies. Many of the observed vibrational term values and rotational constants can be reproduced well with this model. The results show the importance of the Fermi resonance interactions at the high overtone excitations.
24 citations
TL;DR: In this article, a linear relation between the measured signal and the optical absorption coefficient is calculated based on plots on the x,y plane, and the influence of bad thermal contact between sample and detector, thermally thin samples and light scattering samples are investigated.
Abstract: Optothermal and photoacoustic spectroscopy is used for the study of optical properties of liquid and solid samples. The measured signal contains both a phase and an amplitude or equivalent: two components (x and y) with 90 degrees phase difference. The method is based on plotting the measured signal on the x,y plane. Different inversion formulae are presented and investigated by plots in the x,y plane. The formulae are used for the calculation of a linear relation between the measured signal and the optical absorption coefficient. If the thermal properties of the sample are known, an absolute measurement of the optical absorption coefficient can be made. The influence of bad thermal contact between sample and detector, thermally thin samples and light scattering samples are investigated by plots on the x,y plane.
23 citations
TL;DR: In this paper, a high-resolution photoacoustic spectrometer of the gas-microphone type was used to assess polycrystalline CuInSe2 thin films grown by the three-source co-evaporation technique.
22 citations
TL;DR: In this paper, the Fourier transform photoacoustic spectroscopy technique was used to analyze the optical absorption of graphite-epoxy laminate composite material and to enhance the efficiency of laser generation of ultrasound in graphite epoxy.
Abstract: Optical absorption is obviously of prime interest in the efficiency of laser generation of ultrasound in graphite-epoxy laminates. However, no quantitative spectrum of optical absorption in this composite material has yet been published in the literature. Transmission techniques are inefficient, and other techniques, like attenuated total reflectance or diffusive reflectance, do not give absolute values. The Fourier transform photoacoustic spectroscopy technique seems to be a good alternative that can analyze adequately and quantitatively a graphite-epoxy laminate. We used three different methods to compute the absolute optical absorption from the photoacoustic signal. The three methods are: the saturation of the real part of the photoacoustic spectrum, the comparison of the spectra obtained with two different mirror velocities, and the calibration of the photoacoustic cell with a transmission measurement. The spectra obtained in the IR band of 2.5 to 25 μm are presented, and the problems and limitations of each method are discussed. The results permit a better understanding of the absorption process in the composite laminate, and in this way, will help us enhance the efficiency of laser generation of ultrasound in graphite epoxy.
21 citations
TL;DR: In this article, a finite difference model was constructed to describe the origin of the complex transients in pulsed photoacoustic spectroscopy signals, and the model was shown to give qualitative agreement with experimental transients.
Abstract: A finite difference model was constructed to describe the origin of the complex transients in pulsed photoacoustic spectroscopy signals. With inclusion of boundary conditions and material interfaces, the model is shown to give qualitative agreement with experimental transients. The model provides insight into the results of varying the photoacoustic‐cell materials and/or geometric configuration for cell optimization. The transients are found to contain significant information regarding resonant modes in the photoacoustic cell assembly. The transient signal behavior is explained in terms of these resonant cavity modes, and it is determined which cell cavities are relevant to a given time segment of the signal. Analytical detection limits are correlated with each point on the transient signal.
18 citations
Journal Article•
TL;DR: It is found that NCPAS may qualify for the future control of various photoablation and laser parameters such as incision depth, ablation-zone diameter, fluence, and target-material identification and discrimination, and its advantage over competing optical methods is its independence from optical target properties.
Abstract: Photoablation with the 193-nm excimer laser in organic and inorganic material generates an audible sound wave; in a clinical context, this helps to determine when effective photoablation is taking place. We investigated whether the acoustic phenomenon would qualify as a quantitative parameter of photoablation during non-contact photoacoustic spectroscopy (NCPAS). Photoablation was performed with a 193-nm excimer laser at a fluence of 80-330 mJ/cm2 and ablation-zone diameters ranging between 1.2 and 5.13 mm. A capacitor microphone (Broel & Kjaer) emitted a time signal that was processed for Fourier transformation (FT, spectrum of frequency). The following elements of the FT-signal were studied: the integral, the amplitude, the half-value, and the location of the center frequency. The integral and the amplitude were correlated linearly with the fluence. Variation of the ablation-zone diameter between 1.2 and 5.13 mm was found to produce a squared increase of the integral and the amplitude (fluence, 180 mJ/cm2). The half-value and the center of frequency of the FT signal were constant for the same target material but varied between materials. NCPAS may qualify for the future control of various photoablation and laser parameters such as incision depth, ablation-zone diameter, fluence, and target-material identification and discrimination. Its advantage over competing optical methods is its independence from optical target properties (e.g., fluorescence, surface roughness, reflectivity).
TL;DR: In this paper, the Hadamard transform technique has been extended to include photoacoustic detection in the visible spectral region and depth profiling has been illustrated in a layered sample consisting of a thin (20 μm) surface layer of neodymium oxide dispersed in a polystyrene matrix on a thick (2.5 mm) interior layer of holmium oxide dispersed in poly styrene matrix.
Abstract: The Hadamard transform technique has been extended to include photoacoustic detection. The feasibility of Hadamard transform photoacoustic spectrometry in the visible spectral region has been demonstrated. Depth profiling has been illustrated in a layered sample consisting of a thin (20 μm) surface layer of neodymium oxide dispersed in a polystyrene matrix on a thick (2.5 mm) interior layer of holmium oxide dispersed in a polystyrene matrix. Depth profiling may be accomplished by varying the modulation frequency or by phase-sensitive detection at the appropriate modulation frequency.
TL;DR: In this article, a photoacoustic sensor is constructed by using an optical fiber, and the signal is measured as a light transmission loss caused by a microbending effect, and a pressure sensor consisting of a coiled optical fiber is installed in a sample cell for absorption measurement.
Abstract: A photoacoustic sensor is constructed by using an optical fiber. Tie signal is measured as a light transmission loss caused by a microbending effect. The pressure sensor, consisting of a coiled optical fiber, is installed in a sample cell for absorption measurement by photoacoustic spectroscopy (PAS). A frequency-doubled Xd:YAG laser is introduced into the sample cell, and a photoacoustic signal is measured as an intensity decrease of a He-Xe laser beam passed through an optical fiber. The detection limit for a chelate compound of iron II -4,7-diphenyl-1,10-phenanthrolinedisulfonic acid is 1.2×10 -6 M
09 Mar 1993
TL;DR: In this paper, a laser diode was used to test the properties of this laser type as light source for photoacoustic spectroscopy of aerosols, which results in a decreased background signal and an extended modulation frequency range.
Abstract: Up to now photoacoustic spectroscopy is the only available approach for an on-line and in-situ measurement of the absorption of radiation by airborne particles. The main disadvantage of the method is the need for a high-power laser in the visible or infrared spectral region with an optical output of 1 W or more as radiation source to achieve a detection limit for particulate carbon in the order of 1 (mu) g/m3. For the first time to our knowledge a laser diode was used to test the properties of this laser type as light source for photoacoustic spectroscopy of aerosols. The advantages of a laser diode compared with other high-power lasers in the visible are the emission wavelength of 800 nm, the small size of the laser, and the possibility of an electronic intensity modulation of the light instead of a modulation by a mechanical chopper, which results in a decreased background signal and an extended modulation frequency range.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: A single-shot autocorrelation of an ultrashort UV pulse is measured by detecting a two-photon-induced photoacoustic signal in water and the detection sensitivity is higher than that of a multiphoton-induced fluorescence method.
Abstract: A single-shot autocorrelation of an ultrashort UV pulse is measured by detecting a two-photon-induced photoacoustic signal in water. A supersonic wave representing the autocorrelation function is detected by a polyvinylidene fluoride piezoelectric film with a spatial resolution of less than 60 μm. The detection sensitivity is higher than that of a multiphoton-induced fluorescence method by approximately 2 orders of magnitude.
TL;DR: In this paper, the first order approximations of the nonequilibrium mass balance and momentum balance equations are used to predict the temperature and pressure relationship in a photoacoustic effect.
Abstract: The first order approximations of the nonequilibrium mass balance and momentum balance equations allow predictions of the nonequilibrium temperature–pressure relationships in a photoacoustic effect. This is achieved by setting appropriate boundary conditions for the case when frequency of the normal vibrational modes in infrared is significantly greater than the photoacoustic modulation frequency. Based on the internal energy balance equations, the temperature distributions in the gas phase are derived and tested experimentally, allowing quantitative analysis of the photoacoustic FT‐IR spectra.
TL;DR: In this paper, a concept of Intermodulated Photoacoustic Stark Spectroscopy (IMPASS) was used in an attempt to perform the interference-free field measurement of trace ammonia (3 − 40 ppbv) concentration levels in the air with a time resolution of 40 s.
TL;DR: In this paper, photoacoustic measurements of p-Si single crystal annealed at 450°C were carried out at room temperature near an optical absorption edge, where the peak of the pronounced peak at 1.07 eV, which appears only in the p-type samples, becomes smaller and disappear with an increase in the annealing time.
Abstract: Photoacoustic (PA) measurements of p-Si single crystals annealed at 450°C were carried out at room temperature near an optical absorption edge. The height of the pronounced peak at 1.07 eV, which appears only in the p-type samples, becomes smaller and disappear with an increase in the annealing time. Since annealing facilitates the thermal donor formation, the decrease in the peak height is explained by the compensation mechanism of the boron acceptors. The reappearance of the 1.07 eV peak with further annealing at 800°C for 30 minutes, where thermal donors are swept away, firmly supports our explanation.
TL;DR: In this article, photoacoustic (PA) measurements were carried out at 95 K for semi-insulating (SI) GaAs and a broad peak at 0.92 eV and humps in the higher energy region are observed.
Abstract: Photoacoustic (PA) measurements were carried out at 95 K for semi-insulating (SI) GaAs. A broad peak at 0.92 eV and humps in the higher-energy region are observed. Onsets of the humps are at 1.04 and 1.25 eV. Among these structures in the PA spectra, the broad peak at 0.92 eV is partly photoquenched upon illumination of a secondary light (hν=1.12 eV) and thermal recovery occurs after heating to around 150 K. The spatial profiles of this photoquenching along the wafer diameter show a W-shaped distribution. These results indicate that the quenching component of the peak at 0.92 eV in the PA spectra is due to nonradiative recombination of electrons excited from the EL2 level to the Γ-conduction band minimum. The electron transitions involving the EL2 level can be resolved by the PA measurements for the first time.
01 Jan 1993
TL;DR: In this paper, a laser diode was used to test the properties of this laser type as light source for photoacoustic spectroscopy of aerosols, which results in a decreased background signal and an extended modulation frequency range.
Abstract: Up to now photoacoustic spectroscopy is the only available approach for an on-line and in-situ measurement of the absorption of radiation by airborne particles. The main disadvantage of the method is the need for a high-power laser in the visible or infrared spectral region with an optical output of 1 W or more as radiation source to achieve a detection limit for particulate carbon in the order of 1 (mu) g/m3. For the first time to our knowledge a laser diode was used to test the properties of this laser type as light source for photoacoustic spectroscopy of aerosols. The advantages of a laser diode compared with other high-power lasers in the visible are the emission wavelength of 800 nm, the small size of the laser, and the possibility of an electronic intensity modulation of the light instead of a modulation by a mechanical chopper, which results in a decreased background signal and an extended modulation frequency range.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the authors developed a three-dimensional theory of 1he transparent pyroelectric transducer method in photoacoustic spectroscopy (PAS) and showed that the theoretical calculation results are in good agreement with the experimental data of both PA amplitude and phase signals of Si.
Abstract: It is shown that a pyroelectric signal from a transparent transducer, Z-cut LiNbO3, depends on the surface state of the measured sample, a Si wafer. The signal of the Si wafer with the native oxide deviates markedly from the normal pyroelectric signal. Also, we develop a three-dimensional theory of 1he transparent pyroelectric transducer method in photoacoustic spectroscopy (PAS). We discuss the cases in which the pump beam illuminates the sample not only directly, but also through the transducer. It is shown that the theoretical calculation results are in good agreement with the experimental data of both PA amplitude and phase signals of Si. This result indicates that the validity of our theoretical model is verified experimentally.
TL;DR: In this article, the optical properties of fcc C 60 samples have been studied by using photoacoustic spectroscopy over the temperature range 30-300 K. A sharp absorption edge is seen at 1.7 eV at room temperature.
Abstract: Optical properties of fcc C 60 samples have been studied by using photoacoustic spectroscopy over the temperature range 30–300 K. A sharp absorption edge is seen at 1.7 eV at room temperature. The optical absorption spectrum changes drastically at 80 K. Another change of absorption spectrum is also observed at 260 K. These changes can be explained by the molecular motion of C 60 .
05 May 1993
TL;DR: In this paper, laser induced photoacoustic spectroscopy was applied to the determination of 99Tc in a solution coupled with quantitative complexation of Tc with tu (thiourea) to form Tc(tu)6 3+The complexation procedure was adopted to shift the uv absorption peak of pertechnetate to the visible region.
Abstract: Laser induced photoacoustic spectroscopy was applied to the determination of 99Tc in a solution coupled with quantitative complexation of Tc with tu (thiourea) to form Tc(tu)6 3+The complexation procedure was adopted to shift the uv absorption peak of pertechnetate to the visible region, Photoacoustic signals due to the 488 n m absorption peak of Tc(tu)6 3+ was analyzed by using a Past Fourrier Transform (FFT) system. The quantitative detection of Tc could be easily performed down to the 10-8 M concentration in this system. This is about 1,000 times more sensitive than the ordinary colorimetrie measurement.
TL;DR: In this article, the non-destructive depth profiling capability of photoacoustic spectroscopy is exploited in the characterization of the infrared spectra of tissue biopsy samples, and the versatility of the technique is demonstrated.
TL;DR: In this article, laser induced photoacoustic spectroscopy (LPAS) was applied to the determination of T c in a Solution, coupled with quantitative complexation of Tc by thiocyanate ion (NCS~) to form [TC(IV)(NCS)6], which had an intense absorption peak at 500 nm.
Abstract: Laser induced photoacoustic spectroscopy (LPAS) was applied to the determination of \" T c in a Solution, coupled with quantitative complexation of Tc by thiocyanate ion (NCS~) to form [TC(IV)(NCS)6]^\", which had an intense absorption peak at 500 nm. Sensitivity of the quantitative detection could be improved down to a concentration of 10\"® mol dm\"^ which was one Order of magnitude better than that for thiourea complex.
Journal Article•
TL;DR: In this article, the PA spectra of Sm(Ac)3.4H2O, Eu(Ac), Dy3+ and Dy2(Ac)(NO3)4.12H 2O were determined.
Abstract: The complexes crystals of Sm(Ac)3.4H2O, Eu(Ac)3.4H2O and a new complex Dy2(Ac)(NO3)4.12H2O were synthesized and their PA spectra were determined firstly. All their PA spectra absorptions are interpreted. The fluorescence properties of Sm3+, Eu3+, Dy3+ and the relaxation process models were studied by their PA spectra.
TL;DR: In this article, photoacoustic and photothermal spectroscopy methods are applied to the characterization of single microparticles, in which a thermal wave generated by non-radiative transition is detected by deflection of a probe beam.
Abstract: Photoacoustic and photothermal spectroscopy methods can be effectively applied to the characterization of single microparticles. As the optical beam deflection method, in which a thermal wave generated by non-radiative transition is detected by deflection of a probe beam, is sensitive for a single microparticle, and is a remote-measurement method without using a cell, it is suitable for non-destructive characterization of microparticles. This method was applied to determination of chemical species adsorbed on a single microparticle, and spectral differences between leukemia and normal white blood corpuscles could be obtained