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- Cacciani, P, et al.
(author)
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Isotope dependent predissociation in the C-1 Sigma(+) ,v=0 and v=1 states of CO
- 2001
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In: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060. ; 15:1, s. 47-56
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Journal article (peer-reviewed)abstract
- Rotationally resolved spectral lines in the C-X(1,0) band of carbon monoxide are investigated under high resolution using a coherent vacuum ultraviolet laser source, continuously tunable near 107 nm. Transition frequencies are determined by calibrating against a reference standard of iodine lines, recorded with saturation spectroscopy in the visible range, yielding an absolute accuracy of 0.003 cm(-1) in the vacuum ultraviolet. Improved molecular constants for the excited state are clarified and Mo effects of perturbation are found at the present level of accuracy. Line broadening measurements result in information on the excited state lifetime of the (CC)-C-1 Sigma (+),v = 1 state fur five natural isotopomers: of cal bon monoxide: tau((CO)-C-12-O-17) = 280 ps, tau((CO)-C-12-O-18) = 210 ps. tau((CO)-C-13-O-16) = 295 ps, tau((OO)-O-13-O-17) = 160 ps and tau((CO)-C-13-O-18) = 150 Ps. Within the accuracy of the present measurements: Ilo effects: of J-dependent lifetimes: were observed, for neither of the isotopomers. In addition direct time domain measurements: of the lifetime of the C(1)Sigma (+),v = 0 and v = 1 states of the main isotopomer are performed ill a pump-mode experiment using a picosecond VUV-laser, yielding tau((CO)-C-12-O-16) = 1780 ps for v = 0 and tau((CC)-C-12-C-16)) = 625 ps for v = 1. For C(1)Sigma (+), v = 0 in (CO)-C-12-O-16 and (CO)-C-13-O-16 the same lifetime is found; this lifetime matches experimental values of the oscillator strength and hence supports previous results showing pure radiative decay ill this state; the error margins however do not exclude some low level of predissociation. The measurements indicate that the C(1)Sigma (+),v = 0 state of the (CO)-C-13-O-18 isotopomer is predissociated with an estimated yield of 17% (i.e. above the level of predissociation for (CO)-C-12-O-16.) From the combined data predissociation yields: upon excitation of the C(1)Sigma (+),v = 1 state are derived, lying in the range 0.84-0.91. for the five less abundant isotopomers; for the main (CO)-C-12-O-16 isotopomer a strongly deviating predissociation yield of 0.65 is deduced.
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| 2. |
- Descamps, D, et al.
(author)
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Extreme ultraviolet interferometry measurements with high-order harmonics
- 2000
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In: Optics Letters. - 0146-9592. ; 25:2, s. 135-137
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Journal article (peer-reviewed)abstract
- We demonstrate that high-order harmonics generated by short, intense laser pulses in gases provide an interesting radiation source for extreme ultraviolet interferometry, since they are tunable, coherent, of short pulse duration, and simple to manipulate. Harmonics from the 9th to the 15th are used to measure the thickness of an aluminum layer. The 11th harmonic is used to determine the spatial distribution of the electron density of a plasma produced by a 300-ps laser. Electronic densities higher than 2-10(20) electrons/cm(3) are measured. (C) 2000 Optical Society of America. OCIS codes: 190.0190, 190.4160, 190.7110, 120.3180, 140.7240, 350.4500.
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