Showing papers on "Photoacoustic spectroscopy published in 1984"
121 citations
TL;DR: It is concluded that phycocyanin harvests light for both photoreactions but that chlorophyll alpha molecules convey most of their excitation energy to photoreaction I and that about half of the useful energy is stored at stable products.
89 citations
TL;DR: In this article, a self-contained theoretical description of the photoacoustic effect in a thick powdered or porous sample at low modulation frequencies where the sample medium can be considered homogeneous from the point of view of heat diffusion is presented.
Abstract: This paper sets forth a self‐contained theoretical description of the photoacoustic effect in a thick powdered or porous sample at low modulation frequencies where the sample medium can be considered homogeneous from the point of view of heat diffusion. It is shown that the photoacoustic signal results from two contributions: the heat flux from the sample to the gas plus the expansion of the interstitial gas and that the pressure is essentially uniform throughout the sample. Scattering effects are introduced with a Kubelka–Munk modified model and an expression is first given for the conventional partially filled cell. We discuss of these results and their application to the explanation of several texture effects and to the analysis of experimental data. Using a sample composed of chrysotile asbestos powder, we present experimental data and perform an approximate analysis to retrieve the absorption spectrum. Several experimental results are also presented and thoroughly discussed for a cell completely fill...
85 citations
01 Jan 1984
TL;DR: In this article, a review of the theory and application of Fourier transform infrared spectroscopy to the characterization of polymers is presented, where the basic theory, sampling techniques and spectral operations are described.
Abstract: This review covers the theory and application of Fourier transform infrared spectroscopy to the characterization of polymers. The basic theory, the sampling techniques and the spectral operations are described. The applications discussed include the study of polymer reactions, polymer structure and dynamic effects.
64 citations
TL;DR: This "rediscovered" technique provides the following main advantages over the conventional types of spectroscopy: the characterization and analysis of substances in highly light-scattering and opaque materials, and about the life time of the intermediates of chemical reactions.
Abstract: Photoacoustic spectroscopy (PAS), sometimes also termed optoacoustic spectroscopy, is used to study thermal emission resulting from nonradiative de-excitation following absorption of radiation. Several reviews have already been published on the method in general [33, 35, 38, 39, 42] and its application in biology [6, 31]. The detection of the photoacoustic effect dates back to experiments of Alexander Graham Bell [8], John Tyndall, Wilhelm R6ntgen and Lord Rayleigh in 1880. For the history of PAS see [42]. It was not until 1973 that photoacoustic spectroscopy started to be used in a wide range of different applications. This "rediscovered" technique provides the following main advantages over the conventional types of spectroscopy. It allows: 1 the characterization and analysis of substances in highly light-scattering and opaque materials such as powders (drugs, insulators, metals), amorphous solids (glasses), gels (films), suspensions (bacteria, algae, cell organelles) and tissues (leaves, skin), 2 non-destructive and in vivo studies at different subsurface levels of a material (depth profile analysis), 3 studies of the optical and thermal properties of the sample, 4 gathering information about the de-excitation states of molecules (e.g. energy state, quantum yield) and about the life time of the intermediates of chemical reactions. These major advantages make PAS particularly suitable for studying biological material in vivo. In plant material PAS has been used since 1976 for the spectroscopic characterization and detection of pigments in phytoplankton [32] and tissues or cell layers including depth profile analysis [1, 13]. PAS was used for measuring photosynthetic activity by comparing the heat emission of active and inactive sample [e.g. 13, 16]. PAS in combination with
56 citations
TL;DR: In this paper, the oxidation-state specific detection of actinide ions, U(VI, Pu(IV), Pu(VI), and Am(III), was investigated by pulsed laser photoacoustic spectroscopy.
Abstract: The oxidation-state specific detection of actinide ions, U(VI), Pu(IV), Pu(VI), and Am(III), was investigated by pulsed laser photoacoustic spectroscopy. With a single-beam differential technique, the solvent effect is compensated and thus the detection sensitivity substantially increased. The observed detection sensitivities are
49 citations
TL;DR: In this article, the concept of a thermal wave phase shifter for photothermal studies of weakly absorbing samples is described, and the versatility of this technique is demonstrated by spectroscopic studies of neodymium oxide doped poly(methyl methacrylate) film.
Abstract: The concept of a thermal wave phase shifter for photothermal studies of weakly absorbing samples is described. Both sample and reference are excited simultaneously, but their respective photothermal signals reach the detector subsequently. Depending on the phase shift photothermal absorption or transmission spectra can be recorded readily with the same sample. The versatility of this technique is demonstrated by spectroscopic studies of neodymium oxide doped poly(methyl methacrylate) film. At energy fluences in the order of 10 mJ/cm2 sensitivities of 1014 molecules/cm2 are achieved with conventional, unstabilized light sources. The quantum yield for nonradiative decay is determined to be 90% throughout the entire visible spectrum.
44 citations
TL;DR: In this article, a collection of photoacoustic spectra of several readily available stoichiometric rare earth oxide powders is presented, and the J levels of these spectra are assigned.
Abstract: A collection of photoacoustic spectra of several readily available stoichiometric rare earth oxide powders is presented. J levels of these spectra are assigned. In addition to the traditional applications of photoacoustic spectroscopy (chemical, physical, and analytical investigations), the technique is useful for studying the kinetics and thermodynamics of intermediate phases of rare earth oxides and surface photochemical reactions of rare earth oxides. The spectra may also reveal information on the lattice structure of powder grains. The need for additional work in rare earth oxide spectroscopy is pointed out.
33 citations
TL;DR: In this paper, photoacoustic spectroscopy has been used to observe a qualitative depth profile in vitro in mouse skin, which can be used to qualitatively determine the depth of a chromophore in skin.
Abstract: — Photoacoustic spectroscopy has been used to observe a qualitative depth profile in vitro in mouse skin. Because the photoacoustic response is a vector quantity, it can be used to qualitatively determine the depth of a chromophore in skin. The spectrum of an induced layer of β-carotene in albino mouse skin was separated from the spectrum of hemoglobin. Dyes were then used to determine more precisely the position of the β-carotene in the epidermis. The spectrum of melanin was also separated from that of the underlying hemoglobin in pigmented mouse skin.
31 citations
28 citations
TL;DR: Assignments of peaks for both solution- and solid-state proteins are presented and the advantages and disadvantages of the use of near-infrared photoacoustic spectroscopy with proteins are discussed.
TL;DR: In this article, a photoacoustic cell for adsorption spectroscopy on powders is described, which permits spectra to be obtained, with a flowing gas and temperatures up to 400°C.
Journal Article•
TL;DR: Le spectre d'absorption du methanol (10150 a 19900 cm −1 ) and du methane-d (101 50 a 17600 cm − 1 ) was obtenu par spectrometrie photoacoustique intra cavite (PAS).
Abstract: Le spectre d'absorption du methanol (10150 a 19900 cm −1 ) et du methanol-d (10150 a 17600 cm −1 ), a ete obtenu par spectrometrie photoacoustique intra cavite (PAS). A partir d'un modele de vibrations anharmoniques faiblement couplees de modes locaux, les harmoniques de O-H, O-D, C-H ont pu etre attribuees
TL;DR: In this article, the authors used the pulsed photoacoustic technique to measure the effective collisional probabilities for relaxation of the lowest vibrational modes of OCS and CF4 by several collision partners.
Abstract: We have used the pulsed photoacoustic technique to measure the effective collisional probabilities for relaxation of the lowest vibrational modes of OCS and CF4 by several collision partners. The measured probabilities at 300 K are OCS by OCS—(3.7±0.7)×10−4; He—(8.0±0.3) ×10−4; Ar—(0.96±0.3)×10−4; H2—(12.0±7.0)×10−4; D2—(12.9±2.5) ×10−4; N2—(2.5±0.5)×10−4; CO—(3.0±0.7)×10−4; CF4 by CF4—(3.4 ±0.2)×10−4; He—(8.6±1.0)×10−4; Ar—(1.6±0.2)×10−4. We also consider in some detail the acoustic waves generated by cylindrically symmetric laser excitation of a weakly absorbing gas in a cylindrical tube and how the signals produced by a microphone in the tube wall reflect the V‐R,T relaxation of the gas.
TL;DR: In this article, photoacoustic spectroscopy (PAS) was used to measure the thickness of thin SiO2 films grown on (100) Si wafers.
Abstract: Photoacoustic Spectroscopy (PAS) has been used to measure the thickness of thin SiO2 films grown on (100) Si wafers. The data are in reasonable agreement with a simple theoretical model. It suggests that photoacoustic Spectroscopy is complementary to optical interferometry, in that it is capable of giving quantitative estimates of thin transparent films on opaque substrates of low reflectivity via the transmitted fraction of the optical energy incident on the sample. Both theoretical and experimental results indicate that PAS can be very useful in the measurement of thin films on substrates of low reflectivity.
TL;DR: In this paper, the phase shift of the acoustic signal of different constituents is used for a depth profile analysis of layered samples, which is experimentally demonstrated by measuring the phase variations of the photoacoustic detected ferromagnetic resonance of a sample consisting of an iron film bonded to a nickel film.
Abstract: The possibility of using the phase shift of the acoustic signal of different constituents as a new tool for a depth profile analysis of layered samples is discussed. This new method is experimentally demonstrated by measuring the phase variations of the photoacoustic detected ferromagnetic resonance of a sample consisting of an iron film bonded to a nickel film.
TL;DR: A method of measurement of the optical absorption coefficient for a semiconductor sample is given, based on the simplified pattern by Rosencwaig and Gersho in the particular case of thick samples, which allows us to deduce directly the absorption coefficient from photoacoustic amplitude signal measurement, whatever the incident light modulation frequency.
Abstract: A method of measurement of the optical absorption coefficient for a semiconductor sample is given, based on the simplified pattern by Rosencwaig and Gersho in the particular case of thick samples. This method allows us to deduce directly the absorption coefficient from photoacoustic amplitude signal measurement, whatever the incident light modulation frequency. The experimental results obtained from thicker sample of GaP (0.2–1 mm) are compared with the results given by classical optical methods.
TL;DR: In this paper, photoacoustic spectroscopy (PAS) was used for depth profiling in mid-IR by changing the velocity of the moving mirror in a Fourier-transform infrared (FTIR) spectrometer.
TL;DR: In this paper, Fourier transform infrared external reflection and photoacoustic spectroscopy has been used for the vibrational characterization of a Prussian Blue (PB) film on glassy carbon (GC) irradiated at normal incidence.
Abstract: Fourier transform infrared external reflection and photoacoustic spectroscopy has been used for the vibrational characterization of a Prussian Blue (PB) film on Pt and a cupric hexacyanoferrate (CuHCF) film on glassy carbon (GC) irradiated at normal incidence. Since the optical response appeared to be substrate dependent, the mean-square electric fields as a function of the optical constants of the substrates (Pt, GC) and the films (PB, CuHCF) were calculated. The results of these calculations, used with the experimentally determined signal-to-noise ratios, were employed to predict film detection limits. It was found that the electric field intensity near the CuHCF/GC interface was much greater than that near the PB/Pt interface. For this reason, the film thicknesses detectable by these spectroscopic methods are lower at the interface of the GC substrate than at the Pt substrate.
TL;DR: In this article, a technique optoacoustique utilisant une excitation par laser a impulsion is decrite for le dosage d'acetaldehyde dans l'air purifie.
Abstract: Une technique optoacoustique utilisant une excitation par laser a impulsion est decrite pour le dosage d'acetaldehyde dans l'air purifie
TL;DR: In this article, the degradation of polyurethane samples by UV, combination of UV-thermal, and natural weathering were studied by photoacoustic spectroscopy.
Abstract: Degradation of polyurethane samples by UV, combination of UV–thermal, and natural weathering were studied by photoacoustic spectroscopy. This study reveals that degradation of polyurethane could be initiated at a relatively low temperature of 40°C and low UV dosage. It was also found that the effect of heat is more pronounced than the effect of UV. The reaction mechanism of polyurethane degradation is fully in agreement with photoacoustic absorption spectra.
TL;DR: In this paper, a simple Franck-Condon factor model was used to detect the multiphoton ionization and photoacoustic signals from aniline and showed that a given amount of energy can be selectively channeled almost exclusively into either ionization or dissociation pathways.
Abstract: The multiphoton ionization and photoacoustic signals from aniline have been detected as a function of time delay between two laser pulses of different wavelength. The first pulse excited the S0 → S1 0–0 transition. The second pulse either excited S1 to a higher singlet state, or a triplet state produced by intersystem crossing to a higher triplet state, depending on the time delay between pulses. Both ionization and dissociation processes are observed. By varying the conditions of excitation it appears that a given amount of energy can be selectively channeled almost exclusively into either ionization or dissociation pathways. The results are explained using a simple Franck–Condon factor model.
TL;DR: In this article, the energy efficiency of photosynthetic energy conversion in thalli of the green alga Bryopsis maxima was studied with the photoacoustic technique, and the maximum energy yield of 0.4 was obtained with a saturating background light and with a sufficiently weak monitoring light modulated at 100 Hz.
TL;DR: Yamagishi et al. as mentioned in this paper measured the inductive kinetics of fluorescence and photoacoustic signal simultaneously in dark-adapted thalli of the green coenocytic alga Bryopsis maxima under illumination with weak red light modulated at 60 Hz.
IBM1
TL;DR: In this article, a photoacoustic infrared spectroscopy was used to determine the molecular structure of a modified polystyrene (divinylbenzene) surface, which was used as a chromatographic packing material for high performance liquid chromatography.
Abstract: Surface modified polymers are found in a variety of industrial applications ranging from highpower transmission line insulators to chromatographic packaging materials. Infrared spectroscopy has routinely been used to characterize the surface of these materials but often requires sample preparation which may alter the form of the polymer. By using a photoacoustic detector, the infrared spectra of surface modified polymers can be obtained. The polymeric material examined in this study, polystyrene(divinylbenzene), is routinely used as a chromatographic packing material for high performance liquid chromatography. The surface of the polymer was modified to produce surface functionalities more amenable to bonding with a liquid phase than the native copolymer. This paper describes the use of photoacoustic infrared spectroscopy to determine the molecular structure of this modified polymer surface.
TL;DR: In this paper, the use of a pseudo-randomly modulated optical beam and a cross-correlation signal recovery technique to obtain impulse response photoacoustic signals is demonstrated.
Abstract: The use of a pseudo-randomly modulated optical beam and a cross-correlation signal recovery technique to obtain impulse response photoacoustic signals is demonstrated. The application of this technique to provide depth-related physical and chemical information from plant tissues is described.
TL;DR: In this paper, photoacoustic spectroscopy was used to assess the degradation of polyethylene under local natural weathering conditions, and the results obtained were in good agreement with those obtained using infrared spectrograms and from mechanical testing.
Abstract: Photoacoustic spectroscopy was used to assess the degradation of polyethylene under local natural weathering conditions. The results obtained are in good agreement with those obtained using infrared spectroscopy and from mechanical testing. Photoacoustic spectroscopy supports the accepted mechanism of polyethylene degradation.
TL;DR: In this article, photo-acoustic detection has been used to monitor a stimulated emission pumping process in p −difluorobenzene, using the A^(1)B_(2u)5^1 state as an intermediate, several vibrational levels of the ground electronic state were populated.
Abstract: Photoacoustic detection has been used to monitor a stimulated emission pumping process in p‐difluorobenzene. Using the A^(1)B_(2u)5^1 state as an intermediate, several vibrational levels of the ground electronic state were populated. The photoacoustic method is an attractive alternative to other detection techniques because of its sensitivity, simplicity, and its ability to differentiate between stimulated emission pumping and excited state absorption. An example of excited state absorption in aniline is given.
TL;DR: Fourier Transform Infrared Photoacoustic (FT-IR/PA) spectroscopy provides a means to obtain high quality spectra of polyparaphenylene (PPP), an organic semiconductor Spectra of PPP prepared by two different methods, heavily n-doped PPP and a new organometallic derivative, PPP(Mo(CO)3)025 are presented Spectral acquisition times for these polymers can be as low as one minute as discussed by the authors.
Abstract: Fourier Transform Infrared Photoacoustic (FT-IR/PA) spectroscopy provides a means to obtain high quality spectra of polyparaphenylene (PPP), an organic semiconductor Spectra of PPP prepared by two different methods, heavily n-doped PPP, and a new organometallic derivative, PPP(Mo(CO)3)025 are presented Spectral acquisition times for these polymers can be as low as one minute