Quantitative Laser-Induced Fluorescence Measurements of Reactive Species: Spectroscopy and Collision Dynamics of SiCl

1988 ◽  
Vol 117 ◽  
Author(s):  
Jay B. Jeffries
Keyword(s):  
Gas Phase ◽  
Laser Induced Fluorescence ◽  
Rare Gas ◽  
Silicon Etching ◽  
Collision Dynamics ◽  
Species Concentration ◽  
Radical Species ◽  
Fluorescence Measurements ◽  
Vibrational Levels ◽  
Ideal Technique

AbstractLaser-induced fluorescence (LIF) is an ideal technique to determine the gas phase concentration of the chemically reactive radical species in processing plasmas. Quantitative species concentration measurements require spectroscopic and collision dynamics data. Experiments to obtain such data for the B2 and Σ+ B′2 Δ states of SiCl are described. Using LIF, the transition strengths, radiative lifetimes, and collisional removal rates are determined. Collisional transfer between the two excited electronic states, B′→B, shows a very unusual quantum state specificity for the final vibrational levels which is quite different for each of the rare gas collision partners (He, Ne, Ar). Such energy transfer makes the B′2 Δ state unsuitable for quantitative LIF diagnostics; however, the B2Σ+ state appears to be an ideal excited state for LIF diagnostic measurements in silicon etching plasmas.

The ground state of Na2

1989 ◽  
Vol 67 (9) ◽  
pp. 912-918 ◽  
Author(s):  
O. Babaky ◽  
K. Hussein
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Ground State ◽  
Laser Induced Fluorescence ◽  
Rotational Relaxation ◽  
Fixed Frequency ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
Laser Frequencies ◽  
Ion Laser

The laser-induced fluorescence of the [Formula: see text] and [Formula: see text] transitions of Na2 are analysed, using high resolution Fourier transform spectroscopy. Fixed-frequency ion-laser lines (4880 and 4765 Å (1 Å = 10−10 m) from Ar+ and 6471 and 4762 Å from Kr+) together with laser frequencies from a ring dye laser, using rhodamine 6 G with λ = 5781.22 and 5796.80 Å, were used to excite Na dimer in the gas phase. Twenty-eight series of [Formula: see text] and [Formula: see text] systems have been assigned and analysed, and the strong transitions are accompanied by numerous rotational relaxation lines. Molecular constants of the [Formula: see text] state were calculated with high precision from simultaneous least-squares fits to 1410 lines assigned to the A–X and B–X systems. These constants have been used to determine the Rydberg–Klein–Rees potential curve of the X ground state for vibrational levels up to ν = 62.

Gas-phase pyrolysis of trans 3-pentenenitrile: competition between direct and isomerization-mediated dissociation

2021 ◽  
Vol 23 (11) ◽  
pp. 6462-6471
Author(s):  
Piyush Mishra ◽  
Sean M. Fritz ◽  
Sven Herbers ◽  
Alexander M. Mebel ◽  
Timothy S. Zwier
Keyword(s):  
Gas Phase ◽  
Molecular Beam ◽  
Microwave Spectroscopy ◽  
Radical Species ◽  
Flash Pyrolysis

The flash pyrolysis of trans 3-pentenenitrile was studied by mass-correlated broadband microwave spectroscopy, where both molecular and radical species were observed within our jet-cooled molecular beam, including 2,4-pentadienenitrile.

Monitoring of cold and light stress impact on photosynthesis by using the laser induced fluorescence transient (LIFT) approach

2010 ◽  
Vol 37 (5) ◽  
pp. 395 ◽  
Author(s):  
Roland Pieruschka ◽  
Denis Klimov ◽  
Zbigniew S. Kolber ◽  
Joseph A. Berry
Keyword(s):  
Photosynthetic Efficiency ◽  
Light Stress ◽  
Pulse Amplitude ◽  
Laser Induced Fluorescence ◽  
High Light Intensity ◽  
High Light ◽  
Persea Americana ◽  
Effective Quantum Yield ◽  
Fluorescence Transient ◽  
Fluorescence Measurements

Chlorophyll fluorescence measurements have been widely applied to quantify the photosynthetic efficiency of plants non-destructively. The most commonly used pulse amplitude modulated (PAM) technique provides a saturating light pulse, which is not practical at the canopy scale. We report here on a recently developed technique, laser induced fluorescence transient (LIFT), which is capable of remotely measuring the photosynthetic efficiency of selected leaves at a distance of up to 50 m. The LIFT approach correlated well with gas exchange measurements under laboratory conditions and was tested in a field experiment monitoring the combined effect of low temperatures and high light intensity on a variety of plants during the early winter in California. We observed a reduction in maximum and effective quantum yield in electron transport for Capsicum annuum L., Lycopersicon esculentum L. and Persea americana Mill. as the temperatures fell, while a grass community was not affected by combined low temperature and high light stress. The ability to make continuous, automatic and remote measurements of the photosynthetic efficiency of leaves with the LIFT system provides a new approach for studying and monitoring of stress effects on the canopy scale.

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