摘要:

We have developed a new analytical method, which we call the glancing‐incidence and glancing‐takeoff x‐ray fluorescence (GIT‐XRF) method. In this method, a fluorescent x ray is measured at various combinations of incident and takeoff angles. A nondestructive depth profiling is possible by using this GIT‐XRF method, because the effective observation depth is changed by both the incident and takeoff angles. Here, we introduce the idea of depth profiling using the GIT‐XRF method, and then we apply this method to an Au–Si interface reaction. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146163

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We describe an insert for optical and magnetic‐resonance experiments on single molecules in a solid matrix at liquid‐helium temperatures. The experimental arrangement allowsinsituadjustment of the focusing lens and of the sample. A parabolic mirror serves to collect the fluorescence emission and to direct the light onto a photodetector. Microwaves can be irradiated through a coil around the sample while a superconducting magnet provides the possibility of a stationary magnetic field. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146164

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Instrumentation for remote control of the unloaded quality factor,Q0, of a loop‐gap resonator is described. The value ofQ0can be lowered by weak inductive coupling of the resonator to a loop of wire that contains a carbon resistor. Replacement of the resistor by a PIN diode permits remote control. Theoretical analysis and experiments are carried out in a context of electron paramagnetic resonance (EPR) spectroscopy atXband. Equivalent circuits are solved numerically and predicted performance confirmed experimentally. Two applications are demonstrated: (a) superfine control of critical coupling of the incoming transmission line to the resonator in excess of −80 dB, and (b) dynamicQspoiling for reduction of the dead time after a microwave pulse. Possible degradation of EPR system performance by shot noise from the PIN diode is considered. Scant literature suggests that it is very low, and noise from this source could not be detected experimentally. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146165

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have developed aninsituTEM/PL apparatus, which enables us to excite PL emissions from a microscopic area of a specimen inside a TEM. The microscopical area of 20 &mgr;m can be examined by TEM, PL, and CL methods under the same experimental conditions. The apparatus may be applied to a transmission electron microscope of side‐entry type with a minor modification. The apparatus is extremely useful for microscopic characterization of structural and electronic properties in an inhomogeneous material. Utilizing the apparatus, we have examined the spatial distribution of extended defects and point‐defect complexes in CVD diamond. The apparatus will be utilized to study the structural and optical properties of materials under electron irradiation. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146166

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The article describes the ESCA microscopy beamline dedicated to high spatial resolution quantitative and qualitative analysis on surfaces and interfaces. The scanning microscope is constructed to work both in transmission and photoemission within the photon energy range from 200 to 1200 eV with a spatial resolution of ∼0.1 &mgr;m. A Fresnel zone plate demagnifies the photon beam to submicrometer dimensions with 109–1010photons/s in the focus spot. A photodiode and a hemispherical electron energy analyzer are used as detectors for recording the transmitted x‐rays and emitted photoelectrons, respectively. The operation modes in photoemission give the opportunity to obtain conventional energy distribution curve spectra from a microspot or a two‐dimensional micrograph of the spatial distribution and local concentration of a selected element as the sample is mechanically scanned. For conductive specimen topography measurements of a selected surface area probed by SPEM are possible using a scanning tunnelling microscope. The first test images of a zone plate and an e‐beam written specimen with 1 &mgr;m2Au squares on Si have shown a spatial resolution better than 0.2 &mgr;m. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146167

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The applications of the scanning tunneling microscope (STM) in air are usually restricted to good conducting materials as clean metals, doped and passivated semiconductors, or to some molecular adsorbates deposited onto graphite. In order to study poor conducting materials as biological molecules, we have built a very low current STM. This instrument can routinely be operated at 0.1 pA while having a bandwidth of 7 kHz. The advantages of using very low currents are illustrated by imaging 5‐nm‐thick purple membranes. These membranes can only be imaged at currents smaller than 2 pA. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146168

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have developed a large amplitude piezoceramic scanner which should have numerous applications. Scanning tunneling microscopy (STM) and other scanning probe microscopies predominantly use piezoceramics for the scanning elements. Similarly adaptive optics, high resolution lithography, and micromanipulators are other examples of research which regularly utilize piezoceramic scanners. We present a new geometry for a piezoceramic scanner which allows for both high resolution (∼nanometers) and large amplitude (∼400 &mgr;m) displacements. The cross‐shaped geometry makes it possible to produce extremely long pieces with very high tolerances. We have shown its effectiveness by using it as the major component of a low temperature STM (LTSTM). This LTSTM is unique in two distinct ways: the scan range at low temperature is a factor of 10 larger than those reported and the coarse, approach mechanism is a single component piezoceramic—making coarse approachinsitumuch quieter and easier than in other designs. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146169

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Comparative electron polarization measurement with a helium electron polarimeter and a high‐precision Mott detector are presented. For these measurements the helium electron polarimeter was calibrated according to theory, whereas the Mott detector was calibrated independently with an improved auxiliary‐target method. The comparison of the experimental results reveals various problems inherent in helium electron polarimetry, such as poor efficiency and problems occurring in precise light polarization measurements. At present, a high‐precision Mott detector is therefore clearly superior to a helium polarimeter with respect to efficiency and accuracy. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146170

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Most commercial mass spectrometers are intended to select ions by focusing them in one direction by means of electromagnets. However, double focusing is demanded in applications where the pole‐pieces gap is too tight. A mass spectrometer has been planned and built to focus an ion beam in the radial and axial directions using permanent magnets in a circuit with nonparallel pole pieces. Consequently, the magnetic circuit in the spectrometer does not require anyexvacuoconnection for its functioning, and the size can be controlled by just choosing the appropriate magnets. The measurements of the magnetic field configuration show good agreement with the theoretical prediction in the gap radial region where the H−species from a H−surface production experiment are deflected. The description of the criteria followed in the design and construction of the mass spectrometer is the main object of this report. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146526

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Precautions are described for the successful operation of a crossed‐beam apparatus which uses an atomic cadmium target. These include a novel type of high‐voltage trap for the collection of cadmium vapor. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146171

出版商:AIP    

年代:1995

数据来源: AIP