Laser-induced fluorescence spectroscopy for the determination of the absolute density and spatial distribution of Si atoms in a SiH4-He-Ar glow discharge

Abstract

We report on the absolute density and the spatial distribution of silicon atoms in a SiH4-He-Ar dc glow discharge measured by the laser-induced fluorescence method. The absolute sensitivity of the fluorescence-photon-counting system was calibrated by using the same system to measure Rayleigh scattering by Ar gas in the discharge chamber. The fluorescence quantum efficiency and the polarization degree of emitted light were measured to confirm the absence of excited-state quenching induced by collisions with the buffer-gas atoms. The measured spatial distribution profile of the ground-state silicon atoms is compared with that of the excited-state atoms.

PPARγ deficiency results in reduced lung elastic recoil and abnormalities in airspace distribution

“…Airway-parenchymal relationships critically influence the development of obstructive airway disease [7,9]. Litonjua et al [37] and Parker et al [38] determined that the FEF25-75/FVC ratio, a measure of dysanapsis, was negatively associated with the degree of methacholine airway responsiveness, implying small airway size increases the risk of airway obstructive disease.…”

“…Airway hyperresponsiveness is related to the development of asthma and may be genetically determined [39,40]. Additionally, the prevalence of asthma and wheezing negatively correlates with airway size as evidenced by increased prevalence in prepubertal males [41] who have smaller airways [9,42] compared with females. Silverman et al reported that genetic determinants of lung function likely represent determinants of COPD and asthma [43].…”

“…Martin et al determined that dysanapsis did indeed exist in early childhood and remained uniform throughout growth [8]. These variations in airway-parenchymal relationships may influence the development of obstructive airway disease [7,9]. As heritability for airway function exists [1], it is likely that genetic factors contribute to dysanaptic lung growth resulting in a distribution of normal lung function.…”

Study of Spatial Distribution of SiH3 Radicals in Very High Frequency Plasma Using Cavity Ringdown Spectroscopy

“…To understand radical production in SiH 4 /H 2 plasmas, SiH and SiH 2 radicals have been studied under both a-Si:H and mc-Si growth conditions by optical emission spectroscopy (OES) and laser-induced fluorescence (LIF) spectroscopy. [1][2][3][4] Under a-Si:H film growth conditions, the contribution of SiH 3 radicals to a-Si:H film growth and the dynamic behavior of SiH 3 radicals have been studied by means of infrared resonant laser absorption spectroscopy (IRLAS) in a RF plasma with parallel electrodes 5) and by cavity ringdown (CRD) spectroscopy in expanding thermal plasmas. 6,7) These measurements showed that a SiH 3 radical is by far the dominant contributor to a-Si:H growth, due to its higher density and longer lifetime in the plasma than SiH X (X < 3) radicals.…”

Cavity ring down study of the densities and kinetics of Si and SiH in a remote Ar-H2-SiH4 plasma

“…In addition to mass spectrometry, [1][2][3] laser-induced fluorescence ͑LIF͒ based techniques, [4][5][6][7][8][9][10][11][12][13] ultraviolet absorption spectroscopy, [14][15][16] and intracavity 17,18 and infrared laser 19,20 absorption techniques, recently also cavity ring down absorption spectroscopy ͑CRDS͒ has been introduced in the field of SiH 4 plasmas. This sensitive, and relatively easy-to-apply diagnostic technique 21 has already been used for the detection of SiH 3 , [22][23][24] SiH 2 , 18 and nanometric Si-based particles.…”