Showing papers on "Photoacoustic spectroscopy published in 1981"
TL;DR: The theory for a sensitive spectroscopy based on the photothermal deflection of a laser beam is developed and its implications for imaging and microscopy are given, and the sources of noise are analyzed.
Abstract: The theory for a sensitive spectroscopy based on the photothermal deflection of a laser beam is developed. We consider cw and pulsed cases of both transverse and collinear photothermal deflection spectroscopy for solids, liquids, gases, and thin films. The predictions of the theory are experimentally verified, its implications for imaging and microscopy are given, and the sources of noise are analyzed. The sensitivity and versatility of photothermal deflection spectroscopy are compared with thermal lensing and photoacoustic spectroscopy.
1,267 citations
Book•
01 Jan 1981
TL;DR: The recognized leader in the modern development of the field presents both theory and applications as mentioned in this paper, and provides a comprehensive survey of applications, from spectroscopy and chemistry analysis to medical applications and thermal analysis.
Abstract: The recognized leader in the modern development of the field presents both theory and applications. Begins with a historical account, covers gas-phase photoacoustic spectroscopy and detection and the theory of condensed phase photoacoustics, and provides a comprehensive survey of applications, from spectroscopy and chemistry analysis to medical applications and thermal analysis. Treats, for the first time, recent work in high-resolution gas spectroscopy, liquid studies, piezoelectric detection methods, thermal processes, depth profiling, and photoacoustic microscopy.
1,057 citations
TL;DR: In this paper, a method of photothermal imaging was described, which uses optical detection with no contact between specimen and detector, and it was shown that optical detection is more accurate than optical detection.
Abstract: A method of photothermal imaging is described, which uses optical detection with no contact between specimen and detector.
80 citations
64 citations
59 citations
TL;DR: In this paper, the Rosencwaig-Gersho theory of photoacoustic spectroscopy has been expanded into the two-layer model and the photo-acoustic signal in the multi-layer models has been deduced from its approximations in special cases.
Abstract: The Rosencwaig-Gersho theory of photoacoustic spectroscopy has been expanded into the two-layer model and the photoacoustic signal in the multi-layer model has been deduced from its approximations in special cases. Furthermore, the photoacoustic signal is discussed considering multi-reflection of the light in a sample. This calculation accounts for the interference effect on photoacoustic signals. As an example, the interference theory was applied to a sample of silicon on sapphire (SOS), which showed considerable effect of interference.
56 citations
TL;DR: In this article, a simple piezoelectric detection system suitable for performing highly sensitive liquid-phase photoacoustic spectroscopy is presented, and performance of the system with respect to linearity, solvent effects, and excitation pulse characteristics is experimentally evaluated and compared with theoretical figures of merit.
Abstract: A simple piezoelectric detection system suitable for performing highly sensitive liquid-phase photoacoustic spectroscopy is presented. Performance of the system with respect to linearity, solvent effects, and excitation pulse characteristics is experimentally evaluated and compared with theoretical figures of merit. Limits of detection for various porphyrins, laser dyes, and drugs are presented.
55 citations
TL;DR: In this paper, a photoacoustic cell for use with Fourier transform infrared spectrometers is described, showing high sensitivity on a variety of chemical systems and saturation effects can play a prominent role in the photo-acoustic spectra.
Abstract: A new photoacoustic cell for use with Fourier transform infrared spectrometers is detailed. Photoacoustic infrared spectra showing high sensitivity on a variety of chemical systems are presented. Comparison of the photoacoustic infrared spectra with transmission and attenuated total internal reflectance spectra show that saturation effects can play a prominent role in the photoacoustic spectra. Spectral subtractions and study of the situ chemical reactions are possible using the photoacoustic technique. The photoacoustic and diffuse reflectance techniques yield very similar spectra.
55 citations
TL;DR: In this paper, the application of photoacoustic spectroscopy to the spectra of layered samples with thicknesses of tens of microns is demonstrated both theoretically and experimentally, and the theoretical expressions for signal damping and phase delay are developed in terms of the thermal diffusion length, which is determined by the chopper frequency and the thermal properties of the sample.
Abstract: The application of photoacoustic spectroscopy to the spectroscopy of layered samples with thicknesses of tens of microns is demonstrated both theoretically and experimentally. Theoretical expressions for the signal damping and phase delay are developed in terms of the thermal diffusion length, which is determined by the chopper frequency and the thermal properties of the sample. The theory is supported by measurements of both amplitude and phase on a color photographic film containing three light absorbing layers. The application of the method is further illustrated by a simple study of fading leaves.
47 citations
TL;DR: An excellent correlation between the integrating plate (IP) and the photoacoustic methods for measuring aerosol light absorption has been found for airborne graphitic carbon in diesel vehicle exhaust, but the regression coefficient depends on the orientation of the Teflon membrane filter during the IP analysis.
Abstract: An excellent correlation between the integrating plate (IP) and the photoacoustic methods for measuring aerosol light absorption has been found for airborne graphitic carbon in diesel vehicle exhaust. However, the regression coefficient depends on the orientation of the Teflon membrane filter during the IP analysis. With the collected particulates between the filter and the integrating plate, the IP response is 1.85 times that for the filter reversed. In either case the response ratio of the IP method to the photoacoustic method is >1.0, i.e., 2.43 vs 1.30. The IP calibration is also probably dependent on the nature of the filter medium.
42 citations
TL;DR: In this paper, the photoacoustic signal of thin films accounting for the multiple-reflection effect was theoretically derived, and a simple analytical procedure for determining the detailed information on the thermal parameters of the material was presented.
Abstract: We have theoretically derived the photoacoustic signal of thin films accounting for the multiple-reflection effect, and presented the simple analytical procedure for determining the detailed information on the thermal parameters of the material The PAS has been employed on a-Si:H films and the optical absorption spectra down to 1 cm-1 were obtained, which is crucially discussed in comparison with the data by the transmission method
TL;DR: A visible and near-infrared Michelson interferometer has been built to perform Fourier transform photoacoustic spectroscopy and the signal-to-improvement and the performance of the spectrometer are compared with other photoac acoustic methods.
Abstract: A visible and near-infrared (0.36–3-μm) Michelson interferometer has been built to perform Fourier transform photoacoustic spectroscopy. The scanning (step and integrate) and the internal modulation are obtained with only one active element: the moving mirror holder driven by a linear motor. The signal-to-noise improvement and the performance of the spectrometer are compared with other photoacoustic methods and illustrated by various spectra.
TL;DR: It is emphasized that photoacoustic spectroscopy should be concentrated on those applications which are unique for this method, such as depth profiling or special energy conversion such as photochemical oxygen production.
Abstract: Diffuse light scattering is shown, for some well-known examples such as powdered rare-earth oxides and semiconductors, to be a conditio sine qua non for obtaining any wavelength-dependent photoacoustic signal at all. However these photoacoustic spectra have not yet been used to get quantitative values of absorption coefficients obtained using well-known diffuse reflectance spectroscopy techniques. In view of these complications it is emphasized that photoacoustic spectroscopy should be concentrated on those applications which are unique for this method, such as depth profiling or special energy conversion such as photochemical oxygen production.
01 Oct 1981
TL;DR: In this article, the authors describe two different approaches for real-time measurement of diesel vehicle particulate emissions using photoacoustic spectroscopy and long path-length smoke meters.
Abstract: There is a clearly demonstrated need to develop "real-time" methods for the measurement of diesel vehicle particulate emissions. Optical techniques provide one alternative for such methodology because of the rapid data acquisition times involved and the relatively simple sampling methods that can be used. This report describes two different approaches to this problem. The first, the spectrophone, measures light absorption by the diluted exhaust plume using photoacoustic spectroscopy, and the second, the long pathlength smokemeter, detemines total light extinction across the diluted exhaust plume.
TL;DR: In this paper, results from a variety of experiments carried out by the authors on the photoacoustic spectroscopy of solids and surfaces by employing an indigenous spectrometer are discussed in the light of the recent literature.
Abstract: After briefly reviewing the theory and instrumentation, results from a variety of experiments carried out by the authors on the photoacoustic spectroscopy of solids and surfaces by employing an indigenous spectrometer are discussed in the light of the recent literature. Some of the important findings discussed are, phase angle spectroscopy, anomalous behaviour of monolayers, unusual frequency dependence in small cell volumes, spectra of a variety of solids including amorphous arsenic chalcogenides, photoacoustic detection of phase transitions and determination of surface areas and surface acidities of oxides. Recent developments such as piezoelectric photoacoustic spectroscopy, depth profiling and subsurface imaging are also presented.
TL;DR: In this article, photoacoustic spectroscopy (PAS) was used to study intrinsic and extrinsic impurity absorption of semiconductors in bulk, singlecrystal form.
Abstract: Previous work on photoacoustic spectroscopy (PAS) of semiconductors has been restricted to material in powder form. This letter shows that PAS can also be used to study intrinsic and extrinsic (impurity) absorption of semiconductors in bulk, single‐crystal form. For GaAs (Cr) the technique can easily detect Cr impurities at 5×1016 cm−3 level. The effects of surface preparation on the spectra are discussed.
TL;DR: In this article, the authors proposed a method to convert the single beam spectrum into a double beam spectrum by ratioing against the spectral profile of the source radiation as it impinges on the sample.
Abstract: Photoacoustic spectroscopy (PAS) has only recently emerged as a tool for the investigation of the vibrational spectra of condensed matter and surface adsorbates. Qualitative infrared (IR) photoacoustic spectra of various solid materials have been reported both dispersively1–5 and in the Fourier transform mode.6–11 In order to obtain quantitative information from a photoacoustic spectrum (as would be needed to monitor kinetics of surface reactions or for analytical purposes) it is necessary to convert the single beam spectrum into a double beam spectrum by ratioing against the spectral profile of the source radiation as it impinges on the sample. This is called source normalization.
TL;DR: In this paper, a vibration-compensated beam deflection sensing system usable as detector for photoacoustic spectroscopy was described, which is based on the same idea as our system.
Abstract: A vibration-compensated beam deflection sensing system usable as detector for photoacoustic spectroscopy is described.
TL;DR: Fishman et al. as mentioned in this paper proposed an open-ended photoacoustic spectroscopy cell for thin-layer chromatography and other applications, which has been used in a variety of applications.
Abstract: Analytical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Open-ended photoacoustic spectroscopy cell for thin-layer chromatography and other applications Victor A. Fishman, and Allen J. Bard Anal. Chem., 1981, 53 (1), 102-105• DOI: 10.1021/ac00224a026 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 13, 2009
TL;DR: In this article, a new high performance photoacoustic cell was constructed which allows continuous variation of the temperature between 90 K and 320 K. The frequency response of the cell at 90 k and 295 k was examined by means of a carbon black sample.
TL;DR: Small repetitively pulsed lasers can be used with a photoacoustic detection method to obtain linear absorption measurements on optical thin films with a 5 x 10(-5) sensitivity using an acoustic-coupling procedure and with a 1 x 10−5 sensitivity using a liquid-transducer procedure.
Abstract: Small repetitively pulsed lasers can be used with a photoacoustic detection method to obtain linear absorption measurements on optical thin films with a 5 × 10−5 sensitivity using an acoustic-coupling procedure and with a 1 × 10−5 sensitivity using a liquid–transducer procedure.
TL;DR: In this article, photoacoustic measurements have been made at the 4.803 μm absorption line of carbon monoxide in a small nonresonant cell using a low power semiconductor laser source.
Abstract: Photoacoustic measurements have been made at the 4.803 μm absorption line of carbon monoxide in a small nonresonant cell using a low power semiconductor laser source. A simple theoretical model correctly predicts the dependence of the CO signal on chopping frequency and concentration dependence but is inadequate in describing the pressure dependence. Concentrations as low as 50 ppmv were measured by operating the cell in a double pass mode.
TL;DR: In this paper, the temperature dependence of the electronic ground state of solid Fe-(III)-diethyl-dithiocarbamate is investigated for the first time spectroscopically in the visible and ultraviolet spectral range.
TL;DR: In this paper, Fourier transform infrared photoacoustic (FT-IR-PA) spectroscopy was used to obtain the first published infrared spectrum of a heavily n-doped polyacetylene.
Abstract: Fourier transform infrared photoacoustic (FT-IR-PA) spectroscopy has been used to obtain the first published infrared spectrum of a heavily n-doped polyacetylene. Comparisons are made with the FT-IR-PA spectrum of undoped polyacetylene. All the infrared peaks in the FT-IR-PA spectrum of undoped polyacetylene agree in wavelength to ±10 cm−1 with transmission infrared peaks previously assigned by Shirakawa and Ikeda. Spectral shifts and intensity differences between the n-doped and undoped polyacetylene are similar to changes noted previously in the infrared spectra of p-doped polyacetylenes.
TL;DR: In this paper, the Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS) was applied to monitor the photoreactions of a species on the surface including in situ monitoring of reactions involving a gas phase species.
Abstract: : We wish to report the photochemistry of surface-confined -Co(CO)4 fragments exposed to reactive gases. Such photochemistry is of importance in establishing primary events following excitation of the molecular entity attached to the surface and is of relevance to the photoactivation of surface-confined catalysts. We apply, for the first time, the technique of Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS) to monitor the photoreactions of a species on the surface including in situ monitoring of reactions involving a gas phase species. Without any sample manipulation or preparation, this technique has allowed characterization of the photochemistry of surface species with the molecular level specificity generally possible when infrared absorption spectroscopy is used to monitor reactions of metal carbonyls in homogeneous solution. The results herein establish FTIR/PAS as a technique of unequalled capability in monitoring such surface chemistry.
TL;DR: In this article, the authors present a double-beam in-time instrument using a linear scanner-modulator which alternately illuminates the reference and sample held in the same cell.
Abstract: Photoacoustic spectroscopy (PAS)*, the technique of ‘listening’ to the optical absorption by molecules, involves the illumination of a material by light (in the UV-visible--near-IR region) which is ‘chopped’ or modulated at audiofrequencies. Consequently, the heat liberated when the system returns to the ground state through the nonradiative pathway is also periodic. modulated at the same audiofrequency. The resultant pressure oscillations in the gas medium surrounding the sample are sensed by a microphone as acoustic signals. The wavelength dependence of the acoustic signal yields the photoacoustic (PA) spectrum that corresponds, under appropriate conditions, to the optical absorption spectrum. Since it is heat that is detected and not photons, PAS can be used to measure the optical absorption spectral features of light-scattering samples such as solids, surfaces, gels and intact biological specimens. Besides this, PAS can also provide information about the sample such as its thermal diffusivity, depth profile of absorbing species in the material, calorimetric information, excited state lifetime, emission quantum yields, and the action spectrum of photoreactions. The basic theory, instrumentation. and the applications of PAS in chemistry and in biology have been reviewed by several authors during the year [4,19,27,31]. Since its introduction as an analytical tool about eight years ago, PAS has been increasingly used in chemical and biochemical studies, as evidenced by over 80 papers published during the year under review. Photoacoustic spectrometers are commercially available both in the single and double beam models, along with microprocessors for data analysis. The wavelength range accessible is 200-3000 nm. However, home-built instruments are still popular, often with special features such as laser sources, piezoelectric detectors and the like. Two such fabrications of some interest are: (a) a double beam in-time instrument using a linear scanner-modulator which alternately illuminates the reference and sample held in the same cell. and uses synchronous amplification of the difference signal with a single microphone and amplifier set-up [9]. and a somewhat similar construction
TL;DR: In this paper, photoacoustic spectroscopy (PAS), ESR and ir absorption measurements on undoped GD a-Si:H film before and after isochronal annealings, from which absorption coefficient (down to α = 1 cm-1), spin density (Ns) and bonded H content (CH) were determined.
Abstract: We have performed photoacoustic spectroscopy (PAS), ESR and ir absorption measurements on undoped GD a-Si:H film before and after isochronal annealings, from which absorption coefficient (down to α = 1 cm-1), spin density (Ns) and bonded H content (CH) were determined. It has been found out that the extraporated spectrum of spin-free a-Si:H shows a long exponential tail, and that additional broad absorption is strongly correlated with Ns. The origin of α below Eo is discussed.
TL;DR: In this article, the isotopic shift of the ν2 NO3−1 absorption of mixtures of K15NO3 and K14NO3 at 800 and 825 cm−1 has been used to demonstrate that Fourier transform infrared photoacoustic spectroscopy is a technique which is useful for quantitative analysis of solid mixtures.
Abstract: The isotopic shift of the ν2 NO3−1 absorption of mixtures of K15NO3 and K14NO3 at 800 and 825 cm−1 has been used to demonstrate that Fourier transform infrared photoacoustic spectroscopy is a technique which is useful for quantitative analysis of solid mixtures.
TL;DR: In this article, all fundamental transition frequencies to the 25 lowest rotational levels of the ν3 band of HCN have been measured using a photoacoustic spectrometer consisting of an F-center laser, a photo-acoustic absorption cell, and an infrared wavemeter.
Abstract: All fundamental transition frequencies to the 25 lowest rotational levels of the ν3 band of HCN have been measured for the first time to our knowledge using a photoacoustic spectrometer consisting of an F-center laser, a photoacoustic absorption cell, and an infrared wavemeter. The 49 transitions were measured at an HCN pressure of only 20 mTorr and had an rms deviation of 0.002 cm−1 from the calculated values. Effects of pressure broadening and pressure shifts were examined. In addition, the techniques of intracavity photoacoustic spectroscopy and frequency-modulated photoacoustic detection have been demonstrated for studying transitions in this band at low pressure.