Second International Meeting on Photoacoustic Spectroscopy最新文献

{"title":"Photoacoustic Detection of Atmospheric Absorptions Using a cw Ring Dye-Laser","authors":"K. Reddy","doi":"10.1364/pas.1981.mb9","DOIUrl":"https://doi.org/10.1364/pas.1981.mb9","url":null,"abstract":"The intracavity dye-laser photoacoustic-detection technique is extremely sensitive permitting detection of weak absorptions in benzene1 with cross sections as low as 10−27 cm2 at 9.3 kpa (70 Torr) of vapor pressure (absorption coefficient α ~ 10−9 cm−1). The high sensitivity of this technique makes it useful for detecting weak atmospheric absorptions in the near-IR and visible regions. Atmospheric absorption characteristics of high- and low-energy lasers (for example the chemical iodine laser at 1.315 μm and the blue/green laser at 496 nm) are required for selecting and optimizing a particular laser for communications and military applications requiring a long pathlength in the atmosphere. The photoacoustic detection technique is advantageous because it directly measures only the absorption loss which is the principal source of thermal blooming in high-energy laser propagation. Moreover, the small size of photoacoustic cells makes them ideal for quantitative studies of collisional broadening, lineshape, temperature dependence, and the simulation of real-time airborne variations. Similar studies are tedious and time-consuming tasks with large-volume multipass cells.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128684671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoacoustic Studies of the Photocycles of Bacteriorhodopsin at Low Temperatures","authors":"P. S. Bechthold, K. Kohl, W. Sperling","doi":"10.1364/pas.1981.thb2","DOIUrl":"https://doi.org/10.1364/pas.1981.thb2","url":null,"abstract":"Halobacterium halobium is extremely halophilic and requires a high concentration of NaCl (CNaCl > 2M) for growth and maintenance of structure. It occurs in salt lakes (e.g. Dead Sea, salt ponds) and survives even in crystalline salt. Under conditions of limited oxygen supply, 1ight-energy-converting membrane patches, the so-called purple membranes, are synthesized within the outer membrane of the bacteria. The purple membrane contains practically only one protein, called bacteriorhodopsin (BR) (1), which is arranged in a two-dimensional lattice, whose structure is known within a resolution of 7Å (2). BR is a chromoprotein and the pigment of the purple membrane. The purple membrane can be isolated by lysis of the cells and following purification by different centrifugation steps. The chromophoric group of BR is retinal, alternatively either in the all-trans or 13-cis configuration (3). Other retinal isomers were not found in vivo. BR which contains all-trans retinal is called trans BR \u0000BRtrans568, BR which contains 13-cis retinal is called 13-cis BR \u0000BR13-cis548. The two BR isomers are interconvertible by means of several pathways (Fig. 1) (4). One pathway does not require light (‘dark adaptation’); the others are initiated by light. Each isomer forms its distinct primary photoproduct. In the case of trans BR, the photoproduct returns via dark reactions through a series of transients to its initial isomer, trans BR (trans BR cycle). The light-energy-converting process, i.e. the active transport of protons from one side of the purple membrane to the other, can be correlated to the trans BR cycle. The function of the 13-cis BR cycle is not yet known. In the case of 13-cis BR, the dark pathway is split: most of the molecules return to their initial isomer, 13-cis BR (13-cis BR cycle), but some, on an alter native path, go to trans BR. Both pathways are connected by light reaction pathways, which are occupied by photo-excitation of transients. The environmental light conditions determine the isomeric composition of BR. In the dark-adapted state, BR contains a mixture of 13-cis BR and trans BR in a ratio of 1:1. On illumination of a dark-adapted sample with moderate light (e.g. 1mW/cm2), nearly all BR molecules are found in the trans BR state within a few seconds. The photoproducts of each BR isomer can be identified by means of low temperature absorption spectroscopy. To overcome light scattering due to cracks forming in aqueous suspensions at low temperatures, the BR samples have to be suspended in a glycerol/water mixture (w:w = 2:1) for optical absorption measurements. Only photoacoustic spectroscopy enables us to examine the photoproducts and intermediates of the two BR photocycles in buffered aqueous suspensions at low temperatures. We thus obtained photoacoustic spectra of nearly the same quality as optical absorption spectra.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"242 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124665888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of The Photoacoustic Spectroscopy for Measuring The Optical Absorption Coefficient of Liquids","authors":"P. Poulet, J. Chambron, R. Unterreiner","doi":"10.1364/pas.1981.tub12","DOIUrl":"https://doi.org/10.1364/pas.1981.tub12","url":null,"abstract":"When applied to thermally thick samples, the Rosencwaig and Gersho's theory1 gives simple expressions of the amplitude and phase of the photoacoustic signal, which enable the optical absorption coefficient of the liquids to be measured, using either the phase 2 or the amplitude of the acoustic signal3.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122541576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoacoustics in Photosynthesis","authors":"S. Malkin, G. Bults, B. Horwitz, N. Lasser‐Ross, D. Cahen","doi":"10.1364/pas.1981.thb1","DOIUrl":"https://doi.org/10.1364/pas.1981.thb1","url":null,"abstract":"Photosynthesis is a complex process in which light is utilized to split water and reduce carbon dioxide, incorporating inorganic carbon into organic matter. The reaction steps can be divided roughly into two classes, loosely called \"light\" and \"dark\" reactions. The first are involved in oxygen evolution from water and formation of highly reduced (NADPH) and high energy (ATP) intermediates. These serve as the raw materials for the following CO2 reduction and fixation (\"dark\" reactions), contributing reducing equivalents and energy.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131599704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature Dependence of the Quantum Efficiency of Ruby.*","authors":"R. T. Brundage, W. Yen","doi":"10.1364/pas.1981.wa1","DOIUrl":"https://doi.org/10.1364/pas.1981.wa1","url":null,"abstract":"Recently there has been great interest in applying photoacoustic (PA) spectroscopy to the determination of relative and absolute quantum efficiencies in luminescent solids.1-4 We have carried out a series of experiments using PA techniques to measure the quantum efficiency of the 2E→4A2 transition in ruby as a function of temperature from 100 to 300K.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114561192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Extended Helmholtz Resonator in Low Temperature Pas","authors":"J. Pelzl, O. Nordhaus, K. Klein","doi":"10.1364/pas.1981.tub7","DOIUrl":"https://doi.org/10.1364/pas.1981.tub7","url":null,"abstract":"A possible way to realize a PA-cell for measurements at variable temperatures is to separate the sample and the microphone chamber. In order to retain large acoustic amplification of the whole arrangement small gas volumes and resonance type acoustic cells are required. In this work we have investigated experimentally and theoretically PA cells which make use of a narrow cylindrical tube to separate the microphone from the sample. This type of construction has already been applied for low and high temperature PAS by several research groups /1,2/. The present approach proceeds from a generalized treatment of the Helmholtz resonator model which takes into acount the retardation effects in the duct. Here we report on theoretical and experimental results obtained in the temperature range between 10 K and 300 K with the cell arrangement sketched in Figure 1. The low temperature cell consists of two chambers V1 ≅ V2 ≅ 700 mm3 and the connecting tube which has an inner diameter of 1,5 mm and a length 1 = 600 mm. Both chambers are supplied with an electret microphone. The whole construction is designed to fit into an optical cryostat. Room temperature measurements were mostly carried out with air.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114969183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Picosecond Photoacoustics Using an Elliptical Acoustic Cell","authors":"J. Heritier, J. Fouquet, Kenneth Jackson, A. Siegman","doi":"10.1364/pas.1981.tua9","DOIUrl":"https://doi.org/10.1364/pas.1981.tua9","url":null,"abstract":"We report the development of a photoacoustic cell in the form of an elliptical cylinder, in which the acoustic impulse generated by a laser beam passing along one focal line is focused onto a cylindrical piezoelectric transducer located along the other focal line. The sensitivity and clean impulse response of this cell will be employed in photoacoustic experiments presently under way using single and multiple groups of picosecond laser pulses.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121016542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fourier Transform Infrared Photoacoustic Studies of the Chemistry of Organometallic Species Supported on Silica and Alumina Powders","authors":"J. B. Kinney, R. Staley","doi":"10.1364/pas.1981.wa4","DOIUrl":"https://doi.org/10.1364/pas.1981.wa4","url":null,"abstract":"The chemistry of supported cobalt, platinum, chromium, and titanium organometallics has been investigated using a Nicolet Model 7199 Fourier Transform Infrared Spectrometer with photo-acoustic detection. Studies in each system include attachment to high surface area silica and/or alumina powder supports and thermal and/or photochemical reactions with various reagents and molecules. Emphasis is on the behavior of these systems as catalysts.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127988888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design, Properties and Applications of Helmholtz Resonant Photoacoustic Cells for Measurements at Variable Temperatures","authors":"P. S. Bechthold, M. Campagna, J. Chatzipetros","doi":"10.1364/pas.1981.tua11","DOIUrl":"https://doi.org/10.1364/pas.1981.tua11","url":null,"abstract":"Helmholtz resonant cells offer advantages for variable temperature photoacoustic measurements, because they allow to keep the inner volume of the cells small and at the same time to separate the cooled or heated sample from the microphone and preamplifier which can be kept at room temperature(1-3). Since microphones and preamplifiers must not be heated, Helmholtz resonant cells are, in fact, the only appropriate design for high temperature experiments (3,4), while at cryogenic temperatures nonresonant cells may also be used(5). We constructed two resonant cells (2,3) which together are apt to cover the temperature range between 90 K and 1050 K. Both cells are supplied with two small valves used for gas exchange and pressure equilibration. Each cell is equipped with two heating filaments which allow the temperature of the sample to be stabilized with an accuracy better than 0.03 K. Temperatures are measured by Ni-Cr-Ni thermocouples or a platinum resistor.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130598467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of IR Multi Photon Absorption by Polyatomic Molecules Using the Photoacoustic Technique","authors":"S. L. Chin, D. K. Evans, R. Mcalpine, W. N. Selander","doi":"10.1364/pas.1981.mb3","DOIUrl":"https://doi.org/10.1364/pas.1981.mb3","url":null,"abstract":"The single pulse photoacoustic technique for measuring infrared multiphoton absorption by polyatomic molecules is described in detail for the first time. The interaction volume of interest is the focal region (Fig. 1) in which the laser intensity can be very high to promote multiphoton processes. Compared to classical transmission technique with a parallel laser beam of very high intensity (practically very difficult), the present technique is simple but powerful. The microphone detects the energy released from the focal volume in front of it. As long as the microphone is closer to the focal volume than it is to the entrance and exit windows, the signal from the focal region will arrive at the microphone earlier than any other acoustic signal created in the cell. Fig. 2a shows two typical oscilloscope traces at two different time scales of the microphone signal by focusing a 10.6 µ TEA-CO2 laser pulse (~ 1 mJ/cm2) into 3 torr (1 torr = 0.133 kPa) SF6 through a 25.4 cm focal length lens. The focal region in front of the 1.27 cm diameter microphone can be approximated as a cylinder of uniform intensity and length ℓm because of the long focal length. The peak value of the first pulse is proportional to the energy absorbed by the molecules in the focal volume. Three questions are asked. (1) Why is the first peak proportional to the energy absorbed? (2) What are the other oscillations? (3) What is the pressure range for easy application of the technique? The answers are given below.","PeriodicalId":202661,"journal":{"name":"Second International Meeting on Photoacoustic Spectroscopy","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131032927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}