摘要:

A simple electrostatic retarding potential analyzer (RPA) configuration is described that gives a true measure of charged particle energy irrespective of the angle of incidence of the particles. The device has an inherently high energy resolution (&Dgr;E/E<0.01). The device eliminates errors in particle energy measurement usually associated with planar gridded RPAs. Electrostatic models and results from an experimental prototype are presented.

ISSN:0034-6748    

DOI:10.1063/1.1145167

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Two parallel‐plate copper rings with diagonally opposite gaps separated by a dielectric medium form a resonator the natural resonant frequency which is a function of the transmission line propagation constant, its characteristic impedance, as well as the series inductance of the two loops. By means of an extra capacitor connected to each gap, one can easily vary the frequency of the resonator. The derived expressions, valid also for coaxial line devices, relating resonant frequency to other circuit constants, can serve as a tool for those who intend to use this kind of resonator to design NMR surface coil antennas. Experimental results are in good agreement with theory provided the circuit constants are accurately known.

ISSN:0034-6748    

DOI:10.1063/1.1145244

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A simple method is demonstrated for monitoring the time integrated intensity profile of a pulsed laser beam based on desorption from homogeneous films of Rhodamine 6G dye. The method offers micrometer resolution, and for the case of a Gaussian beam profile the fluence scale may be calibrated.  

ISSN:0034-6748    

DOI:10.1063/1.1145214

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An optical free piston cell (a modified le Noble and Schlott type optical cell) is described for use in spectrophotometric study under high pressure. The cell consists of a disk, a cylinder, and a free piston, which are made of quartz and are mounted within a stainless‐steel holder. A small amount of sample solution (∼0.6 cm3), which only contacts with quartz, is required for measurements. The path length is fixed (1.2 cm) at ambient pressure, but is self‐adjusting at elevated pressure so that no compressibility corrections are necessary.   

ISSN:0034-6748    

DOI:10.1063/1.1145114

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A new version of a high‐resolution electron energy loss spectrometer has been constructed. Major modifications are the enlargement of the analyzer, gold coating of all the electrode surfaces facing the electron beam, and the reduction of magnetic fields. A high detector current of 4 pA has been obtained together with the narrow energy half width of 1.2 meV (FWHM) in the straight‐through mode.

ISSN:0034-6748    

DOI:10.1063/1.1145115

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A combined pulse generator and digitizer based on a RISC processor has been designed and tested by59Co NMR. The pulse generator provides a 16‐bit TTL‐level output with 100 ns resolution and is programmable in the high‐level language FORTH. The digitizer supports two channels, each with a 10 bit, 40 MSPS analog‐digital converter and online averaging in a 24×1024 bit memory, which is directly accessible by the RISC processor.

ISSN:0034-6748    

DOI:10.1063/1.1145116

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A large area (1.8 m by 1.8 m), uniform temperature, thermal target was used for characterization of phenomena that impact target contrast. The target board is equipped with several bar patterns. It has a unique design that uses a tilted oven surface making it lightweight with near perfect transition between the hot and cold portions of the bar patterns. The oven surface maintains a ±1 °C uniformity when heated to 10–20 °C above ambient temperature.

ISSN:0034-6748    

DOI:10.1063/1.1145117

出版商:AIP    

年代:1994

数据来源: AIP