摘要:

The open-circuit potential decay (OCPD) technique has been used to get information on:

ISSN:1073-9149    

DOI:10.1080/10739149008543721

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An SFC/MS system has been constructed through additions and appropriate modifications to a GC/MS instrument. Supercritical fluid conditions were effected by transport of liquid carbon dioxide mobile phase through a micro pump to the injector and then into a fused silica capillary column. Two approaches to a successful coupling of the resultant effluent to the GC/MS system in order to yield EI mass spectra have been demonstrated. In one configuration, an open-split GC/MS interface was used to eliminate excess mobile phase. Inside the heated interface was a frit restrictor connected to a deactivated, uncoated fused silica capillary column (also heated) which functioned as a transfer line into the ion source. An alternate configuration omitted the open-split interface and located the frit restrictor inside the ion source. A specially fabricated stainless steel rod, heated by the ion source heater, had a conical opening into which the restrictor tip was positioned and also heated. In both configurations, a turbomolecular pump was used in the ion source. In the above systems, EI mass spectra were satisfactorily produced without ion-molecule contributions or carbon dioxide clusters. The resulting spectra can thus be searched against a conventional mass spectral library for the identification of compounds separated by supercritical fluid chromatography.

ISSN:1073-9149    

DOI:10.1080/10739149008543722

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A technique to determine the surface fractal dimension using a dynamic flow adsorption instrument is described. Fractal dimension is an additional technique to characterize surface morphology. Surface fractal dimension, a quantitative measurement of surface ruggedness, can be determined by adsorbing an homologous series of adsorbates onto an adsorbent sample.

ISSN:1073-9149    

DOI:10.1080/10739149008543723

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

By acquiring data in the form of an excitation - emission matrix (EEM), fluorescence spectroscopy is capable of analyzing multicomponent samples. However due to electronic limitations, earlier designed fluorometers are incapable of acquiring EEM data and new instruments which can acquire EEM data are relatively expensive. To circumvent this problem, an economical hardware interface was constructed, between an older analog fluorometer and a personal computer. The excitation and emission monochromators can now be electronically controlled, monochromator position continuously tracked, and detector output digitized so as to acquire EEM data in a reasonable period of time. Multicomponent EEM spectra of polynuclear aromatic hydrocarbons were acquired as a system test.

ISSN:1073-9149    

DOI:10.1080/10739149008543724

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The understanding of reaction mechanism on electrode surfaces requires fast perturbation techniques. One such elegant method is cyclic voltammetry where a dc voltage ramp is applied on a working electrode and the current so produced is monitored. This current reflects the electron transfer process and is controlled by the chemical reactions that take place before or after the electrode process. Scan rates of the order of 200 mV/s or higher can not be recorded on a conventional fast X-Y recorder due to inertia problems. It is customary to use oscilloscopes with memory in order to record the current and voltage signals. The advanced features of digital oscilloscope enhanced this data aquisition process and are amenable for use with computers. The software developed in BASIC language makes it possible to transfer the data aquired by the oscilloscope to the disk storage of the IBM PC.

ISSN:1073-9149    

DOI:10.1080/10739149008543725

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:1073-9149    

DOI:10.1080/10739149008543726

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:1073-9149    

DOI:10.1080/10739149008543727

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor