摘要:

The subject of photoacoustic spectroscopy is reviewed. The basic areas of instrumentation (excitation sources, acoustic cells, and acoustic detectors) are described, and the specific advantages of various designs and techniques are discussed. Results are presented to highlight the applicability of photoacoustic spectroscopy to a wide variety of spectroscopic measurements. Applications include: linear absorption spectroscopy (vibrational and electronic), reaction kinetics, vibrational overtone spectroscopy, trace analysis, and nonlinear spectroscopy (multiphoton and stimulated Raman scattering). Special emphasis is given to photoacoustic Raman spectroscopy (PARS) and its application to gaseous trace component analysis.

ISSN:0034-6748    

DOI:10.1063/1.1137483

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A convenient, versatile matrix formalism for uncertainty analysis is discussed, and the concepts are illustrated numerically by means of their application to a hypothetical robot apparatus. The importance of uncertainty correlations is emphasized in this treatment which is based upon well‐known statistical laws that govern experimental observations.

ISSN:0034-6748    

DOI:10.1063/1.1137484

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The turbulence induced by a current drawn in a low‐density argon plasma is investigated by microwave scattering and correlation techniques. The azimuthal 30‐GHz scattering system uses a newly designed variable waveguide in order to detect the scattered signal at any angle between 0° and 90°. Both diagnostic methods show that the turbulence is dominated by low‐frequency waves propagating perpendicular with respect to the current. A comparison of these two important diagnostic methods for turbulent plasma is presented.

ISSN:0034-6748    

DOI:10.1063/1.1137485

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A new method of measuring the plasma potential using emissive probes is presented; the ‘‘droop’’ method. This method may be used in a steady‐state experiment in whichTe≫Tw, whereTeandTware the electron and filament temperatures, respectively. The method is based on the observation that the floating potential of an emissive probe depends onTw. A filament temperature which changes in time causes the floating potential also to vary. The proportionality constant between the two is extremely sensitive to whether the probe is above or below the plasma potential. Thus, a floating emissive probe which is allowed to cool can be used to discriminate between voltages above and below the space potential.

ISSN:0034-6748    

DOI:10.1063/1.1137486

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Molecular cesium ions are formed by field ionization from a liquid‐cesium droplet suspended on a tungsten needle. An ion beam containing typically 87% Cs+, 10% Cs+2, 2% Cs+3, and 1% heavier molecular ions Cs+n(n>3) can be extracted from the liquid surface. We identified molecular ions in the beam up to Cs+9by photodissociation with a krypton ion laser. The source operates with reliable long‐term stability and shows a conversion efficiency of liquid metal into gas‐phase ions of >25%.

ISSN:0034-6748    

DOI:10.1063/1.1137487

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A phase fluorometer for the measurement of fluorescence lifetimes was constructed from commercially available components. The instrument was tested by using optical delays of 4 and 2 cm, showing an accuracy of 10 ps. Lifetimes, as short as 0.3 ns, obtained by the quenching of fluorescein by KI, were analyzed with a standard deviation of 3 ps. The lifetime resolving power was checked using mixtures of acridine and quinine–sulphate and least‐squares fitting procedures. Accurate amplitude ratios were obtained with the technique of phase‐sensitive detection [J. R. Lakowicz and H. Cherek, J. Biochem. Biophys. Methods5, 19 (1981)].

ISSN:0034-6748    

DOI:10.1063/1.1137488

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A narrow‐linewidth multimodule KrF discharge laser system is described which is designed to be the front end of an electron‐beam pumped amplifier–Raman compressor high‐power UV laser facility. The discharge laser system consists of an intracavity triple e´talon‐narrowed master oscillator followed by an injection‐locked slave oscillator and two single‐pass amplifiers. The master oscillator has 30 cm of gain length while the three remaining devices utilize 90 cm of gain length. The units are electrically triggered from a high‐voltage multitrigger pulse generator. The pertinent electrical parameters have been determined and are reported. Narrowband output (0.1 cm−1) of 1.6 J can be obtained in 20‐ns FWHM pulses. The small signal gain and saturation intensity of the 90‐cm amplifier modules were measured giving values of 0.115 cm−1and 1.7 MW/cm2, respectively.

ISSN:0034-6748    

DOI:10.1063/1.1137489

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Measurement of the small angles of grazing incidence (between the light beam and the surface), &thgr;=&thgr;pand &thgr;=&thgr;s, that are required to decrease the intensity reflectances of a planar surface of an absorbing isotropic medium for the parallel ( p) and perpendicular (s) polarizations, respectively, from 1 (at &thgr;=0) to 1−&ggr;, where &ggr; is a small predetermined reflectance loss (&ggr;≲0.1), permits simple, explicit, and direct determination of both the real and imaginary parts of the complex dielectric function of the medium at the wavelength of the incident monochromatic radiation.

ISSN:0034-6748    

DOI:10.1063/1.1137490

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A system for the spatial characterization of a laser beam using an optoelectronic imaging device is described. A two‐dimensional photodiode array interfaced to a small computer is used to obtain the image of the beam’s cross section; the peak position, peak intensity, and Gaussian peak width can then be computed and displayed. Details of the array interface, the graphics, and the data‐processing algorithm are provided.

ISSN:0034-6748    

DOI:10.1063/1.1137491

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

This report describes an instrument designed to measure the viscosity, surface tension, and density of liquids at elevated temperature and pressure. The theoretical principles, details of construction and operation, and response of the instrument are discussed in detail. As an example of the accuracy of the data generated by this instrument, the thermophysical properties of molten NaNO3–KNO3have been measured over the temperature range 250–400 °C and are shown to be in excellent agreement with the recommended literature values.

ISSN:0034-6748    

DOI:10.1063/1.1137476

出版商:AIP    

年代:1983

数据来源: AIP