摘要:

The convex side of a curved crystal will diffract a continuous range of x‐ray wavelengths simultaneously. Thus, it is useful for spectral analysis of flash x‐ray tubes or plasmas where there is not sufficient time to scan through the spectrum with a spectrometer. It is also convenient for detecting impurities in x‐ray targets and could be used for x‐ray spectrochemical analysis. The choice of analyzing crystal, the particular diffracting planes, and the orientation of the bending axis allows a considerable versatility in intensity and dispersion including the recording of two or three separate spectra in a single exposure.

ISSN:0034-6748    

DOI:10.1063/1.1684741

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Experimental elimination and determination of the Compton component in diffuse scattering have been made by using crystal monochromated Ag K&agr;radiation and balanced Rh and Ru filters. The K absorption edge of Ru (&lgr;=0.5605 Å) lies very close to the wavelength of Ag K&agr;1(&lgr;=0.5594 Å) so that the intensity obtained using balanced Rh‐Ru filters at scattering angles 2&thgr;>20° is essentially the unmodified Ag K&agr;1scattering. A procedure is outlined for the elimination of the Compton component at lower angles and for conversion of arbitrary intensities into electron units.

ISSN:0034-6748    

DOI:10.1063/1.1684742

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An instrument is described for the measurement of circular dichroism in the vacuum ultraviolet. A magnesium fluoride Rochon prism serves as polarizer and a stress plate modulator is the ¼‐wave retardation element. CD spectra have been recorded to 165 nm, but substitution of two elements in the optical system by available parts is expected to allow further extension of the wavelength region accessible. A previously used less successful system is also described which used a rotating Rochon prism and a Fresnel rhomb.

ISSN:0034-6748    

DOI:10.1063/1.1684743

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A method for increasing the fringe shift resolution of a two‐dimensional optical interferogram by more than an order of magnitude without loss of spatial resolution is described. A Fabry‐Perot cavity is used as an interferometer to increase the number of passes. The sharpened fringes are multiplied in number by using a multimode laser as a light source. The fringe pattern (observed without a lens) is equivalent to that of a Mach‐Zehnder interferometer except that a shift of one fringe corresponds to an optical path length difference of &lgr;/2&agr; (instead of &lgr;) when the cavity lengths are in the ratioL/L0=1/&agr;, and &agr; is the number of excited laser modes.

ISSN:0034-6748    

DOI:10.1063/1.1684744

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A low pressurez‐pinch flash lamp, employing one capacitor and a single spark gap, is described. With an input energy of 2000 J, the pulse width (&tgr;e) of the flash was found to be 1–2 &mgr;sec, exhibiting continuous emission down to 125 nm with a maximum at 250±10 nm. This simple lamp thus provides a convenient, routine photolytic source of pulsed vacuum uv radiation that may be employed in conjunction with kinetic spectroscopy.

ISSN:0034-6748    

DOI:10.1063/1.1684745

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A new technique for studying the relaxation rates of excited atomic states, using a rotating linear detection polarizer, is described. Theoretical expressions for the resultant signals are obtained and a procedure for adjusting the various experimental parameters is explained. This method separates the various coherent signals and provides a large signal intensity with much more convenience and stability than methods previously used.

ISSN:0034-6748    

DOI:10.1063/1.1684746

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

For measurements of the statistical distribution of parameters of pulses (peak amplitude, etc.), a technique is introduced to measure accurately the background due to pulses not correlated in time to the events of interest. This technique is applicable when an event marker signal, correlated in time to the events of interest, is available, i.e., always in time measurements and often in other cases. The basic principle is to make cycles of two successive measurements, in which the probability of measuring a background pulse is the same for both, while the one of measuring an event pulse is much higher in the first measurement; the results of the two measurements must be treated differently. The technique and its applications to amplitude and time measurements are considered in detail. The instrument developed is presented together with some experimental results.

ISSN:0034-6748    

DOI:10.1063/1.1684747

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A rotating cylinder type apparatus is described, suitable for determining drag in cylindrical Couette flow of rarefied gases, and for evaluating tangential momentum accommodation coefficients at gas‐solid boundaries. The apparatus is equipped with a damping device using diffusion pump oil for eliminating undesirable oscillations in the system. Tangential momentum accommodation coefficients of argon on aluminum were determined with an accuracy of ±2.5%. The results obtained indicate that the apparatus may be used over a wide pressure range, corresponding to free molecule and continuum flow conditions.

ISSN:0034-6748    

DOI:10.1063/1.1684748

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Magnetic fields are sensed by means of the Faraday effect. Corresponding electrical signals in phase quadrature are generated. An auxiliary oscillator is used to obtain a phase modulation proportional to the magnetic field to be measured. Demodulation is performed by a phasemeter described in detail. This phasemeter keeps track of multiples of 2&pgr; by digital accumulation and performs linear analog interpolation with an accuracy of 2&pgr;/1000. The hybrid digital/analog output has an arbitrarily wide measuring range. In addition, a purely analog output is provided combining the count of increments of 2&pgr; with the interpolation. The sampling rate of 40 kHz insures fast measurement response. Results of an experimental magnetic field sensing system incorporating the phasemeter as demodulation unit are presented.

ISSN:0034-6748    

DOI:10.1063/1.1684749

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An atomic absorption spectrophotometer has been constructed to provide automated measurement of elemental vapor pressure changes with temperature. Three alloy‐containing absorption cells and a blank reference cell are fixed in a furnace which is automatically moved to position each cell sequentially on the spectrophotometer optic axis, while the furnace independently follows a predetermined time‐temperature profile. Measurements of spectral intensities and thermocouple outputs are recorded at selected intervals and are printed and punched on paper tape. Subsequent computer processing of the punched data yields values of thermodynamic activities and partial molar enthalpies and entropies of the alloy constituents.

ISSN:0034-6748    

DOI:10.1063/1.1684750

出版商:AIP    

年代:1970

数据来源: AIP