Weng Shi-Fu

Localized vibrational mode infrared absorption of BH pair in silicon

Abstract High density of BH pair was produced by interaction between atomic hydrogen and boron in B-diffused silicon. The absorption band of BH pair, at 1873cm-1, was first observed using FT-IR spectroscopy. After thermal treatment at 240°C for 30min. the BH pair dissolved and the carrier concentration increased, the hole mobility decreased owing to the increase in ionized impurity scattering, and the 1873cm-1 absorption band disappeared.

FT-IR Study And Intensity Calculation On The Hydration Of Acetonitrile

During recent years, the FT-IR study on hydration of molecules attracted considerable interests. The peak positions and intensities of IR bands of some molecules change apparently after hydration. The theoretical explanation to these changes, especially to the intensity variation, is rather few. In this investigation, the effect of hydration on the IR intensity of acetonitrile has been systematically studied. Three parts are included: 1. Experiments: CH3CN-CC14-H20 systems were prepared from acetonitrile, tetrachloromethane and water. The volume percents of acetonitrile kept 80% in all solutions and the volumes of water in these solutions were 0.0, 3.0, 6.0, 9.0, 12.0 and 15.0% respectively. The infrared spectra of these solutions were measured quantitatively by Nicolet 7199B FT-IR spectrometer. It was found that the intensity of C-N stretching band(2200 cm-1) became stronger when water was added and the more the water was added, the larger the intensity increase was. This is caused by the formation of hydrogen bond between CH3CN and H20. 2. Normal coordinate analysis: The normal analysis of CH3CN was carried out. It was found that the IR spectrum of liquid acetonitrile could not be explained by the model of C3v symmetry of acetonitrile molecule. This effect on the IR bands is now under investigation. 3. The infrared intensity calculation: The atomic polar tensors (APT s) of CH3CN and CH3CN--H20 were calculated. The APIs of CH3CN were quite different from those of CH3CN--H20. The infrared intensities of C-N stretching bands in CH3CN and CH3CN--H20 were calculated respectively. The increase of IR intensity of C--N stretching band when water was added has been explained to some extent.

On the Tributylphosphate-Based Super-Concentrated HCl System

We reported a new super-concentrated hydrochloric acid system prepared by using tri-n-butyl phosphate (TBP)-constructed reversed micelles at ambient temperature and pressure. According to the titration result, the molar ratio of H+ to H2O (denoted as n(H)+/nH(2)O) in the super-concentrated HCl range from 0. 50 to 1. 50 which are higher than that in saturated aqueous HCl bulk solution (0. 28). Significant a moment of hydrochloric acid is confined in W/O reversed micelles. Therefore, the behavior and status of HCl are different from those of conventional bluk solution. FTIR spectroscopic results demonstrate that a significant amount of HCl remains in the molecular form rather than being ionized into H+ and Cl-. Thus, super-concentrated HCl provides an extraordinary chemical environment which may have significant influence on certain substances. We found that the color of the solution is reddish brown when copper ion is dissolved in super-concentrated HCl, while the color of the saturated HCl aqueous solution (37 Wt%) containing copper ion is green. That is to say, the copper ions exist in a special state under the unique chemical environment of super-concentrated HCl. UV-Vis-NIR spectra indicate that both d-d transition band and charge transfer transition band of copper ions in super-concentrated HCl solution underwent significant variations. In addition, copper ions also have obvious influence on the hydrogen bond network among HCl in the super-concentrated HCl solution. Remarkable variation is introduced in the H-Cl stretching band in FTIR spectra.

FT-IR Spectra Of The C=O And C-H Stretching Vibration Of Lauric Acid

FT-IR spectra of lauric acid in different media were examined. In very dilute solution of lauric acid in CC14, the two bands at 1711 and 1760 cm-1 the region 1650 to 1800 cm-1 were observed for the C=0 stretching modes of dimer and monomer of lauric acid, respectively. In n-butanol KBr pellet and fluorinated hydrocarbon media, the three bands at 1712, 1701 and 1687 cm-1 after deconvolution and curve analysis for the C=0 stretching mode can be observed. In the region of C-H stretching vibration, the wavenumber shifts of the CH2 symmetric and antisymmetric stretching bands of lauric acid in different media show that the packings of acyl chains of lauric acid in different media are not the same.

Effects Of Impurity On The IR Absorption Bands Of Si-H Centers

The IR bands in N-type and P-type floating-zone silicon grown in hydrogen atmosphere before and after neutron irradiation have been studied using FT-IR spectroscopy. The effects of impurity on the IR bands of Si-H centers have been observed.

The Fourier Transform Infrared Spectra Of Liquid Water

Taking the advantage of the high resolving power and sensitivity of the FTIR spectrometer and using multiple scanning technique, we have successfully resolved the stretching vibrational band of liquid water near 3400 cm-1 into 8 peaks of rotational fine structure and determined the molar absorptivities of various vibrational modes.