White light absorption

Since 0.47 MJ of solar energy is trapped as chemical energy in this process, the maximum efficiency for total white light absorption is 28.1%. Further adjustments are usually made to account for the percentages of photosyntheti-cally active radiation in white light that can actually be absorbed, and respiration. The fraction of photosynthetically active radiation in solar radiation that reaches the earth is estimated to be about 43%. The fraction of the incident light absorbed is a function of many factors such as leaf size, canopy shape, and reflectance of the plant it is estimated to have an upper limit of 80%. This effectively corresponds to the utilization of 8 photons out of every 10 in the active incident radiation. The third factor results from biomass respiration. A portion of the stored energy is used by the plant, the amount of which... 

USES OF HIGH-SENSITIVITY WHITE-LIGHT ABSORPTION SPECTROSCOPY IN CHEMICAL VAPOR DEPOSITION AND PLASMA PROCESSING... 

II. High-Sensitivity White-Light Absorption Spectroscopy. 296... 

HIGH-SENSITIVITY WHITE-LIGHT ABSORPTION SPECTROSCOPY 297... 

Fig. 1. Schematic diagram of the hollow-cathode glow-discharge CVD and high-sensitivity white-light absorption spectroscopy apparatus. (Reprinted with permission from Menningen et ai, 1995a, Contrih. Plasma Phys. 35, 359, 1995 Wiley-VCH, Inc.)...

As stated in the introduction, high-sensitivity white-light absorption spectroscopy has been used more extensively in studying the gas-phase composition during the CVD of diamond films than in other applications of CVD. In this section we review the use of high-sensitivity white-light absorption for the measiuement of n for the various free radicals and molecules present in the CVD of diamond under different conditions. 

High-sensitivity white-light absorption spectroscopy was used in the detection of CH3 and C2H2 in the CVD of diamond by Childs et al. (1992) in a hot-filament... 

Menningen et al. (1995a) have studied the CH and CH3 densities in a hollow-cathode dc-discharge CVD reactor. They observed the white-light absorption spectra of CH using either the (0,0) band near 432 nm or the... 

High-sensitivity white-light absorption spectroscopy has been used to measure the CH densities in various CVD reactors. These measurements show remarkable sensitivity. The CH and CH3 densities have been used to obtain the dissociation ratio [H]/[H2]. 

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