Absorption Valley Research Articles

Spectral reflectance of recently fallen chondrites and some igneous rocks in China

Polarization and radiation measurements and microwave studies show that the planets and the great majority of asteroids in the solar system are covered by soils similar to regolith on the moon surface. The soils repesent the composition of the asteroids and the geological elements of the planets. The spectral reflectance shows a tendency of decreasing from near ultraviolet, visible to near-infrared in order of LL → L → H → E with increasing Fe0/Fet rato and toward to absorption for Jilin. Xinyang and Zaoyang ordinary chondrites and Qinzhen enstatite chondrite recently fallen in China. The same chemical group of meteorites feature deeper absorption valleys with increasing metamorphic grade. The spectral reflectance of igneous rocks varies from strong to what is like that of H-group chondrites in order of acid → basic → ultrabasic rocks.

Photoabsorption and direct dissociation cross sections of C2H2 in the 1530–1930 Å region: A temperature dependent study

Using synchrotron radiation as a continuum light source, the absolute photoabsorption and direct dissociation cross sections of C2 H2 in the 1530–1930 Å region have been measured at 295 and 155 K. In comparison with cross sections obtained at room temperature, the cross sections at absorption peaks typically increase by 10%–40% while those at absorption valleys decrease by as much as 30% at 155 K. Further, the absorption band profiles become narrower as the gas temperature decreases. In the presently studied wavelength region, there are at least three electronic states, namely, the à 1 Au , the B̃ 1 Bu , and a continuum. Using the present low temperature data we have constructed the repulsive potential energy curve of the direct dissociation state according to the Franck–Condon principle. The potential energy curve thus constructed can be more accurate than that constructed by using room temperature cross section data because only the absorption cross section from the ν′=0 level contributes. The present cross section data have also been used in the analysis of oscillator strength distribution.

Estimation by Infrared Spectrophotometer of the Calcium Oxalate Dihydrate to Calcium Oxalate Monohydrate Ratio

According to the theoretical expression for calibration curve as a function of the optical absorption ratio of two peaks and with the analysis of the infrared spectra of the mixture samples of commercial calcium oxalate monohydrate and synthesized calcium oxalate dihydrate, the following quadratic equation was obtained;Y=1.79 X2−30.90 X+107.04in which Y is the percentage of the purity of calcium oxalate dihydrate and X is the ratio of the relative optical absorption at 660cm−1. (the wave number at a characteristic absorption peak of calcium oxalate monohydrate) to that at 610cm−1. (that of c_alcium oxalate dihydrate) by regarding the line as a base-line that links the absorption valley at around 700cm−1 with that at 550cm−1. The linear correlation coefficient of the actual purity to the estimated purity obtained from this formula of calcium oxalate dihydrate is 0.995.When this formula is applied to the results derived from the infrared spectra of the mixture samples of commercial calcium oxalate monohydrate and calcium oxalate dihydrate obtained from urinary stones in duplicate in each percentage, the linear correlation coefficient is 0.991.This estimation method by infrared spectrophotometer of the calcium oxalate dihydrate to calcium oxalate monohydrate ratio gave a very close correlation between actual and estimated purity of calcium oxalate dihydrate and seems useful in the study of calcium oxalate urolithiasis.