摘要:

A new design for an ESR spectrometer, using strain modulation, is presented. The novel features are: (i) The sample is nonresonant, so that single crystals of any size and shape can be investigated; (ii) the loss in mechanical Q‐factor, due to the nonresonant technique, is compensated for by using an electrostrictive ceramic (with high piezoelectric constants) instead of quartz; (iii) the whole transducer is kept outside the microwave cavity; (iv) the modulator can be used also at low temperatures (1.2 <T< 400 K). Some illustrative applications are given.

ISSN:0034-6748    

DOI:10.1063/1.1686458

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A velocity spectrum is obtained by dispersing the photoelectrons with a uniform electrostatic field; it is recorded on an electronographic film with the help of an electronic camera. To each point of the plate correspond definite values of the tangential and normal velocities of photoelectrons. The angular and energetic distribution N(W, &phgr;) is calculated from the density of the electronographic plate. We hereby show the first structures obtained from thin films of gold.

ISSN:0034-6748    

DOI:10.1063/1.1686459

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Detailed information about the construction and design of a combined ion source is given. By the use of an exchangeable ion exit slit for the ionization chamber the source is constructed to operate either at a source pressure of about 1 Torr for chemical ionization or at lower source pressures for electron impact ionization, field ionization or field desorption. The potentialities of this source are demonstrated by the mass spectra of a peptide as obtained with the different ionization modes.

ISSN:0034-6748    

DOI:10.1063/1.1686460

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A small retarding field analyzer for Auger electron spectroscopy is described. The resolution and sensitivity for chemical investigations is tested with Pd/Ni alloys and adsorbed oxygen.

ISSN:0034-6748    

DOI:10.1063/1.1686461

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A high time resolution (HTR) electron detector has been developed for use in sounding rocket studies of the aurora. The detector is used to look for particle bunching in the range 50 kHz–10MHz. The design uses a Johnston Laboratory MM‐1 electron multiplier and an onboard frequency spectrum analyzer. By using the onboard analyzer, the data can be transmitted back to ground on a single 93 kHz voltage‐controlled oscillator. The detector covers the 50 kHz–10 MHz range six times per second and detects modulation on the order of a few percent of the total electron flux. Spectra are presented for a flight over an auroral arc.

ISSN:0034-6748    

DOI:10.1063/1.1686462

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A compact vacuum cell and associated optics used to obtain a single‐reflection infrared spectrum of a thin film on a metal surface is described. Reflection‐absorption spectroscopy, in the past, has usually involved multiple reflections. Single reflection setups offer advantages of simplicity, the ability to generate and/or clean the sample surface, and the ability to use other surface studies techniques along with ir. An optical setup is described which will allow the above three advantages to be obtained, and in addition is simple and compact. Along with the optics, a vacuum cell housing the sample is described. This cell fits conveniently with a standard infrared spectrometer and no additional modification to the spectrometer is required.

ISSN:0034-6748    

DOI:10.1063/1.1686463

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Two original and unique optoelectronic systems used to measure the anelastic properties of materials are described. The systems are used in conjunction with a standard inverted torsional pendulum. One system measures low frequency internal friction and the other measures stress relaxation at constant strain. The circuit diagrams and mechanical setups for these systems are given and typical data are shown.

ISSN:0034-6748    

DOI:10.1063/1.1686464

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We present design and construction details of an all solid‐state power supply suitable for dc electromagnets in the impedance range 500–1300 &OHgr;. Current is limited to a conservative 2 A. Current control is implemented through a series element consisting of cascaded, water‐cooled power transistors isolated and regulated to operate at equally spaced voltage intervals within the transistor voltage rating. Current regulation is estimated to be a few parts in 105for a 10% voltage or load change. Conversion of existing tube‐type power supplies to this configuration is detailed.

ISSN:0034-6748    

DOI:10.1063/1.1686465

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The characteristics of some quadrupole coils are examined to determine their suitability for NMR pulsed field gradient diffusion measurements. They are found to be capable of acceptable field gradient uniformity, low ratio of inductance to field gradient strength, low dc resistance and their windings are as far as possible from adjacent pole faces, thus minimising eddy current formation. An improved current pulser using SCR's is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1686466

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A new idea is put forward which reduces considerably the timing errors arising out of the photomultiplier pulse‐amplitude variations. A bipolar signal, obtained at the output of a simple electronic circuit, intersects the time‐axis at a point determined by the amplitude of the input pulse. This amplitude‐dependent displacement of the intersecting point along the time‐axis helps reduce considerably the time fluctuations of the final output signal. Output pulse‐amplitude variations from more than 3 V down to 0.15 V show an almost complete suppression of the time fluctuations of the output signal, while this is only of the order of 25 psec for an input variation of 0.15–0.10 V. The influence of the variation of temperature on the circuit behavior has also been investigated.

ISSN:0034-6748    

DOI:10.1063/1.1686467

出版商:AIP    

年代:1974

数据来源: AIP