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The kinetics of nitromethane in the initial C-H stretching overtone region was examined at intense high resolution utilizing a molecular beam laser spectrometer to determine the intramolecular vibrational energy redistribution (IVR) rate of the C-H stretch. It was observed that the spectrum of the C-H stretching element contained three types of band. It observed that the IVR rate of the different JKaKc levels in the spectrum ranged from 170 to 300 ps equivalent to the rate calculated for methyl C-H stretching overtones in molecules of similar size.

The first stretching overtone region of short-lived, formerly inaccessible BiH[sub 3] near 3405 cm-1 has been measured by Fourier-transform infrared spectroscopy with a resolution of 0.0066 cm-1. Only the 2ν[sub 1](A[sub 1])/ν[sub 1]+ν[sub 3](E) band system has been observed. Rotational analysis, with transitions reaching J[sub max][sup ′]=14, has revealed almost perfect local-mode behavior for the upper states denoted as (200A[sub 1]/E) in the local-mode notation. Ratios of vibration–rotation interaction parameters q[sub eff]/α[sub eff][sup (BB)] and r[sub eff]/α[sub eff][sup (BC)], and the appropriate rotational constant differences, are in good agreement with theoretical local-mode limit values. A simple stretching vibrational model reproduces the observed vibrational term values well, and the potential parameters obtained are close to true values. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Analyzes the overtone vibrational spectra of all T[sub d] symmetry isotopomers of methane. Choice of coordinates and the redundancy problem; Basis states; Symmetry adapted basis; Result of the wave numbers computed with the ab initio force constants.

Constructs an internal coordinate Hamiltonian model to model torsional motion in the OH stretching vibrational overtone region of methanol. Harmonic couplings between OH and CH stretching vibrations; Fermi resonance interactions between OH stretches and COH bends.

Light-emitting diodes (LEDs) have been useful in evaluating plants's physiologic and growth responses to radiation quality and quantity. In the great majority of these studies, growth rooms (phytotrons) have been used in order to avoid the influence of external factors such as the daylight radiation. The main objective of this study was to evaluate the growth performance of two LED-based supplemental lighting treatments (LED1, LED2) on lettuce (Lactuca sativa var. crispa L., 'Frillice') cultivation in real glass greenhouse conditions. Control plants were grown under conventional high-pressure sodium (HPS) lamps. In LED1 treatment red-orange (RO) and blue LEDs with peak wavelength emissions at 630nm and 460nm, respectively were used while in LED2 an additional yellow component at 594nm was also included. The results had indicated that lettuce growth parameters can be improved using supplemental spectral-tailored LED lighting. RO LEDs were also effective in promoting biomass accumulation and the addition of a small percentage of yellow photons may further enhance this aspect and increase the number of leaves per plant. The results have also suggested a relation between the amount of blue photons and yellow-green photons in lettuce growth. [ABSTRACT FROM AUTHOR]

Analyzes the high resolution Fourier transform infrared (FTIR) spectra of the (1000A[sub 1]/F[sub 2]), (2000A[sub 1]/F[sub 2]), and (3000A[sub 1]/F[sub 2]) band systems of [sup 120]SnD[sub 4]. Validity of alpha relations between parameters; Conclusions on rotational analysis and appearance of FTIR spectra; Observation of vibration localization.

An equilibrium structure and an empirical anharmonic force field based on an ab initio surface are obtained using available experimental vibration–rotation data. Four of the six harmonic and four of the ten cubic force constants have been determined experimentally. The remaining values have been fixed at the ab initio values. A good fit to high resolution experimental data is obtained. [ABSTRACT FROM AUTHOR]

Ab initio calculations on HOCl have been performed at the third-order Mo\ller–Plesset perturbation theory level to determine the equilibrium structure and the anharmonic force field. An empirical anharmonic force field based on the ab initio results is obtained using available experimental vibration–rotation data. Four of the six harmonic and six of the ten cubic force constants have been determined experimentally, the remaining values being fixed at the ab initio values. A good fit to the experimental vibration–rotation data of four isotopic species is obtained. [ABSTRACT FROM AUTHOR]

A high resolution Fourier transform infrared spectrum of methyleneimine, HN=CH2, has been obtained in the gas phase in the region 700 to 1300 cm-1. The rovibrational line intensities of the three lowest fundamentals ν7 (A’), ν8 (A‘), and ν9 (A‘) have been simulated including all Coriolis interactions between the three bands, and by fitting the observed spectrum the relative signs and magnitudes of the vibrational transition moments have been determined. All of the available spectroscopic data have been used to determine the harmonic force field of methyleneimine. [ABSTRACT FROM AUTHOR]

The nature of the rotational energy level structure of the stretching vibrational states in XY2, XY3, and XY4 molecules (belonging to the C2v, C3v, and Td point groups, respectively) has been investigated in a local mode limit with no kinetic or potential energy copling between the bond oscillators and with the fundamental stretching frequencies much larger than the bending frequencies. The Coriolis effects between the rotational levels in the stretching vibrational states disappear in this limiting case, but the H22 resonance terms are seen to be important owing to the multiple vibrational degeneracies. Simple relationships are obtained between the coefficients of the vibrationally diagonal and off-diagonal H22 terms and consequently the number of independent molecular parameters is reduced. The model is compared with experimental data for XHn hydrides, and particularly in the molecules with a heavy central mass the major contribution to the H22 coefficients is well explained. [ABSTRACT FROM AUTHOR]

The infrared spectrum of methyleneimine, CH2NH, has been observed in the gas phase with a resolution of 0.0048 cm-1 using the National Optical Observatory solar Fourier transform spectrometer. The CH2NH was produced by the pyrolysis of CH3NH2 at ∼1000 °C. Vibrational band origins and rotational constants have been determined for the ν7, ν8, and ν9 bands. These were analyzed as a set of three states strongly coupled by Coriolis interaction. More than 2500 transitions were assigned, of which many are ‘‘forbidden’’ transitions, such as qQ branches, induced in the ν9 band by the strong Coriolis interaction between ν7 and ν9. Owing to the high precision of the data, and the high J values of many of the observed transitions, it was necessary to include many of the high order interaction constants in order to achieve a quantitative fit. [ABSTRACT FROM AUTHOR]

Year-round greenhouse production in northern latitudes depends on the use of artificial lighting. Light emitting diodes provide a promising means to save energy during cultivation as well as to modify the light spectrum to regulate the growth and quality of the crop. We compared the effects of light emitting diode lighting with different spectral compositions on the growth, development and nutritional quality of lettuce (Lactuca sativa L. ‘Frillice’). We show that warm-white and warm-white supplemented with blue spectra provide equal growth and product quality compared to conventional high-pressure sodium lighting in the absence and presence of daylight. Our data indicate that for biomass accumulation, the far-red component in the light spectrum is more critical than green light or the red/blue ratio. Furthermore, we demonstrate that a red + blue spectrum increases the concentration of several vitamins in lettuce. However, biomass accumulation using this spectrum was insufficient when daylight was excluded. [ABSTRACT FROM AUTHOR]

Along with the high energy-efficiency potential, light-emitting diode (LED) lighting provides the possibility for spectrum control. Our study presents the original data on the influence of LED light spectrum quality on the growth and macro- and micro-nutrient uptake of lettuce (Lactuca sativa L. cv. Frillice) plants cultivated in indoor conditions and without daylight. Four LED light spectral combinations were investigated using conventional high-pressure sodium (HPS) lighting as a control. In general, the LED light spectra were more favourable than the HPS light spectrum for promoting the growth and nutrient uptake of plants. In particular, the light spectrum provided by the combination of the far-red, deep-red and blue LEDs had the highest growth and nutrient uptake indices. This spectral combination particularly enhanced the uptake of potassium, calcium and magnesium in comparison to control plants grown under conventional HPS lamps. The uptake of iron and zinc were significantly influenced by the spectral changes of the red and blue light. [ABSTRACT FROM AUTHOR]

In mesopic photometry, adaptation luminance is needed to derive the mesopic luminances for the measurement field. The average luminance of the visual adaptation field is considered as the adaptation luminance. The visual adaptation field has yet to be defined in terms of the size, shape, or location within the visual field. A study in three road lighting situations was conducted, in order to determine the feasibility of using the road surface as the adaptation field compared to circular or elliptical adaptation fields. Currently, the road surface is used as the measurement field for calculating road lighting. Using the road surface as the adaptation field resulted in 76-113%, higher average luminance than obtained using circular or elliptical adaptation fields when the road was bordered by a park. Highluminance sources outside of the visual adaptation field cause veiling luminance. Veiling luminance increases the adaptation state, but not the luminance within the measurement field. The bias veiling luminance can cause on mesopic luminance calculations was estimated to be less than 2%. The estimated bias can be considered trivial in practical road lighting measurements. [ABSTRACT FROM AUTHOR]