I2 Absorption Research Articles

Observation of NO B 2Π(v=3)←X 2Π(v=0) absorptions with 1+1 multiphoton ionization: Precision line position measurements and parity assignment of the B 2Π state

Absorptions are observed in the β(3,0) band of NO, B 2Π(v=3)←X 2Π(v=0) using 1+1 multiphoton ionization at photon energies in the range 47 801–48 542 cm−1. Line positions are reported in 10 of the 12 possible branches with an accuracy of 0.05 cm−1, directly traceable to the visible I2 absorption spectrum. Λ doubling in the β(3,0) band is explicitly resolved, allowing a definitive parity assignment of the B 2Π(v=3) rotational levels. Accurate term energies and molecular constants are presented for B 2Π(v=3). Comparison with previous measurements reveals significant discrepancies. Line positions are also reported in the γ(2,0) band, A 2Σ+(v=2)←X 2Π(v=0), of the 14N18O and 15N16O isotopes.

Stoichiometry and electrical charge transport in HgI2 crystals

Stoichiometry of vapor-grown HgI2 (mercuric iodide) crystals has been studied quantitatively using Raman spectroscopy and liquid solution spectrophotometry. Evaluation of mercury excess is based on differentiation between the Raman spectra of HgI2 and Hg2I2 (mercurous iodide). Iodine excess is determined by dynamic dissolution of HgI2 in CC14 (tetrachloromethane) and measurements of the characteristic I2 absorption intensity at 517 nm. The threshold for stoichiometric analysis has been lowered to about 10 ppm, which is an order of magnitude better than that achieved by other methods. Crystals grown from starting materials subjected to the standard purification by repeated sublimations, melting and additional sublimation have been found nearly stoichiometric regardless of the synthesis method of the compound. It is shown that both mercury and iodine rich crystals can be grown by controlling the composition of the starting material or the growth atmosphere. Large excess of either mercury or iodine ( > 100 mole ppm) causes a noticeable deterioration in the energy resolution of HgI2 nuclear radiation detectors, which is discussed in terms of trapping of radiation-induced charge carriers by nonstoichiometric defects. The kinetics of trapping have been studied using the transient charge technique.

On the centre-to-limb variation and latitude dependence of the asymmetry and wavelength shift of the solar line ? 5576

Low noise photoelectric measurements of the line profile of the g = 0 Fe line gl 5576.097 combined with determinations of the wavelength shift of its centre calibrated by use of an I2 absorption tube are reported. Measurements taken at various limb distances (1.0 ≤ cos ϑ ≤ 0.2) and along 4 different diameters of the Sun are used to investigate the behaviour of the line asymmetry (C-shape) and wavelength shift of the line centre as functions of cos ϑ and of latitude and to search for possible pole-equator differences.

Rat Bladder Irrigation with PVP-I2

Despite technical advances, Foley catheter associated urinary tract infections continue to be the leading cause of nosocomial infections. PVP-I2 has been shown to be nonirritating to abraded tissue and we have shown that dilute solutions are bactericidal for organisms causing Foley catheter associated urinary tract infections. The purpose of this study was to ascertain the toxicity of PVP-I2 on the catheterized rat bladder and to measure the systemic absorption of I2. Bladder catheters were surgically placed into each of 3 groups of rats: group 1, catheters only; group 2, irrigation with PBS q.8h; and group 3, irrigation with a 1:3 dilution of a 10 per cent PVP-1 per cent I2 solution q.8h. One-half of each group was sacrificed at 1 and 2 weeks respectively. Photographs of mounted bladders and histologic sections were then graded by 3 independent observers. Blood for protein bound iodine (PBI), T3 and T4 levels was obtained before the study and at sacrifice. No difference in ulcerations, erythema or inflammation was noted. PBI was higher in group 3 rats at conclusion than group 1 and 2 (6.88mg./dl. versus 3.42mg./dl.) (p < 0.05). There was no difference in T3 or T4 levels. In this study, PVP-I2 was no more toxic to the bladder than catherization alone or irrigation with PBS.

Investigation of an I2(D'–A') laser pumped by wide-band radiation

An experimental investigation was made of an ultraviolet I2 laser with an energy of 13 J in a 12-μsec pulse and an average specific output energy of ~10 J/liter. An analysis was made of the processes occurring in the Using cycle, the density of the excitation spectrum was estimated, and rates were obtained of the relaxation of the vibrational energy of the excited states and of the depopulation of the lower active state. The conditions under which a steady-state population inversion can exist in an I2 laser during continuous pumping were established. The maximum attainable efficiency was estimated to be ~1% for the pump source employed. The efficiency of conversion of the pump radiation energy in the I2 absorption band into laser radiation energy amounted to at least 6%. The quantum efficiency of lasing was not less than 11%. When the fluorescence was included, it was found that the quantum efficiency for the D' state of I2 was several times higher.

Two- and three-photon absorption of I2

Abstract Two and three-photon absorption of I2 is studied in the gas phase. The emission band at ≈340 nm is attributed to the 1432, 2g(3II) → 2431, 2u(3II) transition, and the 385 nm band to the 1g(3II) → 1u(3II) transition. The 270 and 290 nm bands correspond to states promoted by three-photon absorption.

Removal of I_2 absorption lines from 514-nm excited Raman spectra

The intense excitation of an Ar(+) laser operating at 514 nm enhances the grating ghosts and general stray light within most double monochromators at wavelengths close to the exciting line. The I(2) filter technique provides an effective means of reducing this interference and, in so doing, makes possible the measurement of Raman bands close to the exciting line. However, at an instrument resolution less than 3 cm(-1), the I(2) absorption spectrum seriously interferes with the Raman spectrum. Ratioing the Raman spectrum with a white light absorption spectrum of I(2) removes the I(2) absorption lines. However, with slit widths <3 cm(-1), the wavelength reproducibility of the monochromator on successive scans is not high enough to insure successful ratioing. A technique is described for obtaining, approximately within the same time interval, the Raman spectra and white light spectrum at each wavelength that data are acquired. This procedure accurately removes the I(2) absorption spectrum.

Single-mode operation of an Ar+ laser with an intracavity I2 absorption cell

A multi-mode argon ion laser was furnished with an intracavity127I2 absorption cell for the purpose of mode suppression at the wavelength of 514.5 nm. Singlemode operation was achieved with an 8 cm long cell having a127I2 vapour pressure of 0.27 mbar (0.2 Torr).