Laser beam attenuation in LIF measurements on NO in a diesel engine

The effect of laser beam attenuation on nitric oxide measurements in a diesel engine is presented. A number ofexperimental ways to correct for this attenuation are discussed: transmission measurements, bidirectional laserinducedfluorescence, and Raman scattering by N2. Comparison of the results indicates that the attenuation isgenerally not uniform over the cylinder. Instead it seems to be less severe over the field of view (i.e. the upper partof the cylinder)

Laser beam attenuation in LIF measurements on NO in a diesel engine

The effect of laser beam attenuation on nitric oxide measurements in a diesel engine is presented. A number ofexperimental ways to correct for this attenuation are discussed: transmission measurements, bidirectional laserinducedfluorescence, and Raman scattering by N\u3csub\u3e2\u3c/sub\u3e. Comparison of the results indicates that the attenuation isgenerally not uniform over the cylinder. Instead it seems to be less severe over the field of view (i.e. the upper partof the cylinder)

Quantitative nitric oxide measurements by means of laser-induced fluorescence in a heavy-duty Diesel engine

Quantitative in-cylinder laser-induced fluorescence measurements ofnitric oxide in a heavy-duty Diesel engine are presented. Special attention is paid to experimental techniques to assess the attenuation of the laser beam and the fluorescence signal by the cylinder contents.This attenuation can be considerable at certain stages in the combustionstroke. The temperature and pressure dependence of the fluorescence signal is described in various models. In this study, LIFsim was used.Finally, calibration was realized by concentration measurements in the exhaust gas

Doppler-Free Spectroscopy of Weak Transitions: An Analytical Model Applied to Formaldehyde

Experimental observation of Doppler-free signals for weak transitions can be greatly facilitated by an estimate for their expected amplitudes. We derive an analytical model which allows the Doppler-free amplitude to be estimated for small Doppler-free signals. Application of this model to formaldehyde allows the amplitude of experimentally observed Doppler-free signals to be reproduced to within the experimental error.Comment: 7 pages, 7 figures, 1 table, v2: many small improvements + corrected line assignmen

Rotational Cooling of Polar Molecules by Stark-tuned Cavity Resonance

A general scheme for rotational cooling of diatomic heteronuclear molecules is proposed. It uses a superconducting microwave cavity to enhance the spontaneous decay via Purcell effect. Rotational cooling can be induced by sequentially tuning each rotational transition to cavity resonance, starting from the highest transition level to the lowest using an electric field. Electrostatic multipoles can be used to provide large confinement volume with essentially homogeneous background electric field.Comment: 10 pages, 6 figure

The structure of the phenol-nitrogen cluster. A joint experimental and ab initio study

Contains fulltext : 59287.pdf (publisher's version ) (Open Access

High-resolution spectroscopy on the a-similar-1b1(0, 6, 0) - x-similar-1a1(0, 0, 0) transition in sicl2

Contains fulltext : 99065.pdf (publisher's version ) (Open Access

High-resolution cavity ringdown spectroscopy of the jet-cooled ethyl peroxy radical C2H5O2

Contains fulltext : 75140.pdf (publisher's version ) (Open Access

Rotational isomers of hydroxy deuterated o- and m-cresols studied by ultraviolet high resolution experiments

Contains fulltext : 32948.pdf (author's version ) (Open Access)The laser induced fluorescence spectra of several torsional transitions of the S-1 ← S-0 electronic transition were recorded for the hydroxy deuterated o- and m- cresols. Both cis and trans rotamers were observed in a high resolution molecular beam experiment. The spectra were analyzed using a genetic algorithm assisted automatic assignment. The Hamiltonian used included rotational, torsional and rotation - torsion components. Both, high resolution rotationally resolved spectra and low resolution torsional frequencies, were combined to obtain the rotational constants, the direction of the methyl group axis, and the V-3 and V-6 barriers to internal rotation of the methyl top in the ground (S-0) and excited (S-1) states. The lifetime of the S-1 state is also reported. Quantum interference effects due to the interaction of the internal and overall rotation allowed for determination of the absolute sign of the angle between transition moment and the a principal axis