摘要:

A lateral sample modulation technique is presented to measure simultaneously lateral friction forces and topological features with an atomic force microscope (AFM). The employed technique allows one to use an AFM without any additional displacement sensor. This dynamic detection scheme is well suited for AFMs equipped with a fiber‐optic displacement sensor. The technique and the mechanism of the contrast formation are discussed. The performance of the microscope is demonstrated by imaging flat surfaces and large corrugated films as well as low friction samples.

ISSN:0034-6748    

DOI:10.1063/1.1144630

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The accuracy of measurement of the thickness of uniform thin films on solid substrates by null ellipsometry is severely limited when the substrate is rough. It is impossible to separate these two effects experimentally with the null ellipsometer, and there is no theoretical basis or generally used model available to separate these effects. Thus, a dual rotating‐compensator Mueller matrix ellipsometer has been constructed to carry out film thickness measurements on rough substrates. Measurements were made on a set of specially prepared specimens of 8630 steel, roughened by grit blasting with aluminum oxide. Grit sizes and blasting pressures were varied to produce 11 different roughness values ranging from 0.01 to 1.295 &mgr;mRa, as measured with a stylus tracer device. Upon each of the 11 roughness groups, films of magnesium fluoride were overlaid to thicknesses of 89, 180, 254, and 315 nm. One set of specimens was left uncoated. Experimental results for film thickness measurements on rough surfaces matched the ideal (for smooth surfaces) form well for roughnesses up to 0.13 &mgr;mRa, at most angles of incidence. For rougher specimens, significant deviations in results were observed for all but the largest angles of incidence. The nonideal data were attributed to the cross‐polarization effects of surface geometry, and apparent depolarization. The resolution of thickness measurements was 1 nm for polished specimens, and decreased continuously to 10 nm for the roughest specimens examined.  

ISSN:0034-6748    

DOI:10.1063/1.1144631

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A computer‐controlled rotating polarizer ellipsometer, operating in the infrared spectral region between 3.00 and 3.75 &mgr;m, has been developed forinsitucharacterization of amorphous hydrocarbon (a‐C:H) thin films, deposited from methane in a rf plasma‐enhanced chemical vapor deposition reactor. Spectroscopic IR ellipsometry permits insight into the chemical bonding structure ofa‐C:H coatings by the nondestructive detection of infrared stimulated C:H stretch vibrations. It is shown that thesp2CHx/sp3CHxratio, the content of bonded hydrogen, the infrared linewidth, and the real refractive index of the films depend on the negative self‐bias voltage, which is formed at the samples during the deposition process. A transition froma‐C:H films with polymerlike properties to harda‐C:H films was attained at a self‐bias voltage of approximately −75 V.

ISSN:0034-6748    

DOI:10.1063/1.1144632

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present a new method for measuring time‐resolved photoluminescence on a time scale of microseconds and milliseconds using correlational analysis, and we demonstrate it to work on porous silicon and GaP:Fe. We modulate the pumping laser with a pseudorandom binary sequence which yields correlational properties similar to white noise. The photoluminescence decay is computed via cross correlation of the detector signal with the pumping sequence. The presented method is highly sensitive, simple in application, and inexpensive.

ISSN:0034-6748    

DOI:10.1063/1.1144633

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A new characterization method of materials processed by ion beams or laser beams using a two‐color interferometer with two frequency‐doubling optical crystals is described, based on the dispersion property of the materials. Resolution of measurement is improved to an optical phase of 1° (subnanometers) by use of a heterodyne technique with acousto‐optic modulators.

ISSN:0034-6748    

DOI:10.1063/1.1144634

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present a methodology to retrieve the thermal diffusivity of bulk homogeneous samples based on a set of simple linear relations that exist between two measurable magnitudes in modulated photothermal experiments. The influence of the photothermal parameters involved (exciting beam radius and height and radius of the probe beam) is evaluated to assert the validity of the linear relations. Specifically, we discuss the thermoreflectance and mirage techniques and their more convenient use and method, depending on the kind of sample to analyze (solid, liquid, gas), to obtain the thermal diffusivity.

ISSN:0034-6748    

DOI:10.1063/1.1144635

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The transient hot‐wire method for simultaneously measuring the thermal conductivity and thermal diffusivity of materials has been modified to improve the accuracy of the measurements. In this new experimental method, called the multicurrent method, several constant current values are used for heating the hot wire in order to determine accurately the thermal transport quantities. The details of the multicurrent method are precisely described, and examples of experiments using the method with pure water, electrolytic solution, and ionic conducting glasses are given. It is shown that this method can be used both for liquid and solid materials; a relatively small amount of the specimen material is sufficient for each experiment; the material can be insulating as well as highly ionic‐conductive; the accuracies of the determined thermal conductivity and the thermal diffusivity values are, respectively, around ±1% and ±5%.

ISSN:0034-6748    

DOI:10.1063/1.1144636

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A commercially available flat flame burner with a sintered porous bronze disk was used to stabilize premixed H2/air flames at atmospheric pressure. Temperatures for various stoichiometries, flow rates, and heights above the burner disk have been measured by coherent anti‐Stokes Raman scattering with an accuracy of ≊2.5%. The corresponding exhaust gas compositions have been derived from equilibrium calculations. This burner together with the data presented in this article can be used for the verification or calibration of a variety of measuring techniques in combustion research.

ISSN:0034-6748    

DOI:10.1063/1.1144637

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A noncontact cryogenic microwave measurement system has been developed for the characterization of passive and active superconducting devices by means of an unloaded quality factor measurement technique. The measurement system was designed specifically for the characterization of planar thin film resonant structures as a function of temperature (4–300 K), frequency (100 MHz–26.5 GHz), and dc voltage bias (≤100 V). It has been used for basic device studies of novel active superconducting lumped components made of metal‐oxide superconductor/insulator heterostructures.

ISSN:0034-6748    

DOI:10.1063/1.1144638

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Electrical LC resonators with superconducting coils of ≊3.5 H inductance, operating in the frequency range 250–1500 Hz with quality factors up toQ≊1.6×106are presented here. The coil has a reduced, <100 pF, stray capacitance and is housed in a superconducting case. Measurements are made with a low coupling SQUID readout. Some possible applications of the device are briefly discussed.

ISSN:0034-6748    

DOI:10.1063/1.1144639

出版商:AIP    

年代:1994

数据来源: AIP