摘要:

Described in detail is a laser induced fluorescence system which has been successfully interfaced with two aircraft sampling platforms (i.e., Sabreliner jet and an L‐188C Electra). This system, which has been under development for four years, presently consists of the following major components: (1) a Nd–Yag laser driven oscillator–amplifier dye laser; (2) a sampling manifold with associated fluorescence detection optics; (3) an OH calibration chamber; (4) a laser beam steering assembly; and (5) sampling electronics and data processing hardware. During the last three years, this system has been flown some 50 000 air miles making tropospheric OH radical measurements over the latitude range of 70 °N to 57 °S. OH concentrations measured during these flights have ranged from 30 parts‐per‐quadrillion (3.7×105molecules/cm3) at altitudes of 6 km to 0.8 parts‐per‐trillion (2.0×107molecules/cm3) at 0.5 km. Computations have been completed which indicate that the existing aircraft system with modest modifications should also be capable of detecting natural tropospheric levels of NO, SO2, CH2O, NO2, HNO2, NO3, H2O2, and CS2by using both conventional laser‐induced fluorescence methodology and multiphoton techniques.

ISSN:0034-6748    

DOI:10.1063/1.1135765

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A mass analyzer having a scanning electron microscopy (SEM) mechanism and using electron beam bombardment vaporization ion source have been submitted. Secondary ions from the surface trapped in the potential well formed by the incident electron beam can be guided into the slit of mass analyzer through the center of Ta pipe cathode. Efficiency of the collected ions to the evaporated molecules and a qualitative mass analysis with a pressed block of powdered NaCl have been examined. When subsidiary electrodes added above efficiency showed 6.4×10−4. A sample of 10‐mm‐thick NaCl has been analyzed along depth direction to the bottom with 0.02 mA at 5 kV in 16 min.

ISSN:0034-6748    

DOI:10.1063/1.1135766

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

In order to detect low‐level NMR signals by bridge methods, a phase displacing device based on principle of voltage addition has been developed allowing the precise bridge balancing over a one decade frequency range. Using analogous multiplier devices for control and adjust circuit the phase adjustment of the output voltage is within ±3° over a frequency range from 10 to 100 kHz. For input peak‐to‐peak voltage levels from 0.1 to 1 V the output level is amplitude‐stabilized to within 2% for all phase displacements.

ISSN:0034-6748    

DOI:10.1063/1.1135767

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An automatic system is described for measuring two‐dimensional acoustic velocity fields in solid samples. The measurement is performed by a computer‐controlled, mechanically scanned transducer in a liquid bath, and is based on measuring the phase delay of the acoustic wave by a two‐pulse echo method. Applications include measuring stress fields due both to externally applied and residual stresses, and microstructure studies of solid samples.

ISSN:0034-6748    

DOI:10.1063/1.1135768

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An optical multichannel system is described, used for time‐dependent absorption measurements in the gas phase and the liquid phase and for resonance Raman spectroscopy of short‐lived transient species in the liquid phase in pulse radiolysis. It consists of either an image converter streak unit or an image intensifier coupled to a TV camera with computerized data handling. The system enables the recording of time‐dependent absorption spectra or resonance Raman spectra of short‐lived radicals and excited states with single electron and light pulses.

ISSN:0034-6748    

DOI:10.1063/1.1135753

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We present a new design for a waveguide laser which is easily constructed from readily available materials. We have demonstrated its operation for CO2(8.5‐W output) and N2O (1.5‐W output).

ISSN:0034-6748    

DOI:10.1063/1.1135769

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A novel photopreionization‐stabilized discharge scheme was developed to excite rare gas halogen excimer lasers with beam energies of 100–250 mJ. The scheme requires no auxiliary timing or switching circuits and provides for the construction of compact and reliable devices.

ISSN:0034-6748    

DOI:10.1063/1.1135754

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

In this paper, the optimization of continuous wave nuclear magnetic resonance in two component flowing mixtures to determine theinsituvolume fractions and the individual component flow rates is described from both an analytical and an experimental point of view. A simple and accurate measuring system is discussed and the analytical and experimental results are compared for oil–water mixes. The use of a relatively long polarizing magnet prior to the highly homogeneous detector magnet has been shown to improve the flow‐rate range considerably and makes feasible a relatively inexpensive, accurate, and genuine two‐phase or two component flow meter. By measuring the optimum value ofH1, or the rf level required to produce that optimum value, and by simultaneously measuring the magnitude of the signal at that time, both theinsituvolume fraction and the flow rate can be determined. This is provided that there is no chemical reaction between the two components and that they travel at the same average velocity. The system may be also used for monitoring changes in constituency of a single substance since the optimum value ofH1depends upon this constituency.

ISSN:0034-6748    

DOI:10.1063/1.1135755

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A method has been developed to produce seamless, freestanding plastic cylinders with dimensions up to 18 cm in diameter, 4 cm in height and with mass density from 15 &mgr;g/cm to 300 &mgr;g/cm (approximately 0.15 to 3 &mgr; thick). The polyvinyl formal resin may be subsequently coated with a variety of material by vapor deposition. The method employs standard thin‐foil fabrication techniques modified for use in cylindrical geometry and results in uniform reproducible cylinders.

ISSN:0034-6748    

DOI:10.1063/1.1135756

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Several major improvements have been made to a Michelson‐type microwave interferometer operating at a frequency of 140 GHz. An enlarged dielectric cell, an improved measuring system, and a highly stable microwave system allow a precise determination of the complex dielectric constant for low‐loss liquids. The effect of a mismatch in the microwave system is discussed and the computed behavior of the instrument is compared to that found experimentally. An experimental technique is described which takes account of the effect. Some results are presented for various solutions of nitrobenzene in benzene and for the alkane series of hydrocarbons. The values obtained are compared with values reported by other workers using different methods.

ISSN:0034-6748    

DOI:10.1063/1.1135757

出版商:AIP    

年代:1979

数据来源: AIP