摘要:

Characteristics of an adapted commercial optical multichannel analyzer system for recording of transient absorption spectra in single‐shot pulse radiolysis and flash photolysis are described. The features discussed include temporal (2 &mgr;s) and spectral (1 nm) resolution, signal‐to‐noise ratio and its improvement, linearity of response, and wavelength coverage (300–650 nm). The system is intermediate in both cost and capabilities compared to two other methods: (1) recording transient spectra by repetitive pulsing and (2) using an image converter streak camera. This system is convenient for discrimination of small differences in fine structured absorption of spectra short‐lived species.

ISSN:0034-6748    

DOI:10.1063/1.1138398

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A high‐resolution picosecond transient absorption spectrometer utilizing dye emission and a streak camera is presented and compared with other methods of picosecond transient absorption measurements. Typical transient absorption and ground‐state bleach recovery kinetics measured with this spectrometer are shown. Single wavelength transient absorption or ground‐state bleach recovery kinetics are determined on the basis of a single laser shot with this spectrometer, so that the samples are relatively free from decomposition by irradiation. Excellent kinetics may be obtained from the near UV to the near IR and are not subject to interference from luminescence of samples. The sensitivity of this spectrometer is very high and it is reasonably easy and convenient to set up and use.

ISSN:0034-6748    

DOI:10.1063/1.1138399

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An apparatus is described for measuring visible absorption spectra across the lateral dimension of a cryogenic matrix isolation sample. By exploiting the rigidity of the matrix, the spatially resolved spectra can be parametrically labeled by another experimental variable, such as photolysis wavelength from dispersed radiation, resulting in a multiplex advantage in data collection rates. Alternatively, the apparatus can be used to measure the visible absorption spectrum of a spatially uniform sample in ≤1 second, a speed which is important for photochemically active samples.

ISSN:0034-6748    

DOI:10.1063/1.1138400

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The technique of laser fluorescence spectroscopy at the Lyman‐alpha (L&agr;) wavelength in hydrogen was used to measure the temporally and spatially resolved atomic density, the surface recombination coefficient &ggr;, and the diffusion coefficient DH,H2of the atomic hydrogen in molecular hydrogen. At the same time, it revealed a temporal change of &ggr;, probably due to the change of surface number density of trapped hydrogen atoms. The present technique provides a new and powerful means for determinations of values associated with hydrogen atoms by absolute and local measurements of the atoms at the detection limit of extremely low concentrations.

ISSN:0034-6748    

DOI:10.1063/1.1138401

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A novel sample switching device for laser Raman difference spectroscopy (LRDS) has been designed for use with nonresonant samples. The device utilizes a single motor driven rotating mirror, fabricated by diamond turning techniques, which switches both exciting and scattered light 60 times per second. Electronic timing signals are obtained to gate photon counting pulses into separate scalers. The use of fixed capillary sample cells allows for the first time in LRDS the examination of fibers, single crystals, and liquid samples of 10‐&mgr;l volume and improved access to samples for thermostating, etc. Alignment of the optics is described. Proper operation of the system is illustrated by examination of pyridine and pyridine‐d5. Comparing spectra of the neat liquids and a mixture of them gives examples of a frequency shift of <1 cm−1, a width change, and other bands with no changes. Advantages, limitations, and future extensions of the instrument are described.

ISSN:0034-6748    

DOI:10.1063/1.1138402

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A polarization modulation ellipsometer for measurements of the complex dielectric function of opaque and reflecting materials in the wavelength range 230–920 nm is presented. The instrument can be built at relatively moderate cost but offers reasonable accuracy. It is suitable for routine measurements in a general solid‐state laboratory because of its easy handling and maintenance.

ISSN:0034-6748    

DOI:10.1063/1.1138403

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A differential polarization microscope forms two images: one of the transmitted intensity and the other due to the change in intensity between images formed when different polarizations of light are used. The interpretation of these images for linear dichroism and circular dichroism are described. The design constraints on the data acquisition systems and the polarization modulation are described. The advantage of imaging several biological systems which contain optically anisotropic structures are described.

ISSN:0034-6748    

DOI:10.1063/1.1138354

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The Mueller matrix approach is used for designing, analyzing, and evaluating a new polarization‐modulation spectrometer for simultaneous measurements of circular dichroism (CD) and optical rotatory dispersion (ORD). The same approach is applied to commercial CD spectropolarimeters for the evaluation of their performance in order to clarify our new spectrometer. On the basis of the results obtained, our JASCO J‐500 CD spectropolarimeter was converted into the new spectrometer. Preliminary experiments indicate that CD and ORD can be measured simultaneously above 400 nm. It is also shown that this new spectrometer can be used for measuring linear dichroism and linear birefringence simultaneously.

ISSN:0034-6748    

DOI:10.1063/1.1138355

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Multichannel fast scanning diode array spectrometers represent a new class of spectroscopic instruments. They feature a unique combination of novel technologies, speed, comfort in handling, and ease of operation. In a research study the potentials of this powerful instrument in the field of microscope photometry are evaluated. As examples for possible applications the results of typical spectral measurements in absorption and reflection, including film‐thickness determination of microstructured semiconductor layers, are presented.

ISSN:0034-6748    

DOI:10.1063/1.1138356

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A compact and inexpensive technique is reported for a discharge‐excited pulsed metal vapor laser (MVL) at a low operating temperature utilizing an air‐blown‐type spark‐gap switch. A laser is excited in an aperiodic pulse train by successive pulsed discharges of a storage capacitor through a spark‐gap switch. A variety of neutral metal vapor laser (MVL) using metal compound as a lasant is briefly reported with the compact device.

ISSN:0034-6748    

DOI:10.1063/1.1138357

出版商:AIP    

年代:1985

数据来源: AIP