| 1. |
- Ubachs, W, et al.
(author)
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Lifetime measurements on the c '(1)(4)Sigma(+)(u), v=0, 1 and 2 states of molecular nitrogen
- 2001
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In: Chemical Physics. - 0301-0104. ; 270:1, s. 215-225
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Journal article (peer-reviewed)abstract
- Excited state lifetimes of c(4)('1)Sigma (+)(u), upsilon = 0-2 states of molecular nitrogen have been determined in a laboratory investigation using a picosecond XUV laser in a pump-probe configuration. For c(4)('1)Sigma (+)(u) upsilon = 0 the lifetime is tau = 740 +/- 50 ps, for the lowest rotational states. For higher rotational states a gradual shift towards tau = 495 ps is found in agreement with previous findings that these states are subject to predissociation. For c(4)(') Sigma (+)(u) upsilon = 1 no J-dependence is found and values for two isotopomers are reported: tau = 240 ps for (NN)-N-14-N-15 = 240 ps for (NN)-N-14-N-15. For c(4)('1)Sigma (+)(u) upsilon = 2 a lifetime for the lowest rotational states (J = 0-3) was derived: tau = 675 +/- 50 ps; for J = 11 a lifetime of tau less than or equal to 120 ps is deduced. All values for the lifetimes including the J-dependences are explained in a model based on Rydberg-valence interaction. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 2. |
- 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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| 3. |
- Cacciani, P, et al.
(author)
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Predissociation of the 4p pi L-1 Pi Rydberg state of carbon monoxide
- 2002
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In: Chemical Physics. - 0301-0104. ; 282:1, s. 63-73
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Journal article (peer-reviewed)abstract
- Time-domain and frequency-domain spectroscopic experiments have been performed on the (4ppi)L(1)Pi, v = 0 Rydberg state in three isotopomers of carbon monoxide. Accurate values for the excited state lifetimes of the f-parity components have been determined: tau((CO)-C-12-O-16) = 1.08 +/- 0.05 ns, tau((CO)-C-13-O-16) = 72 +/- 10 ps and tau((CO)-C-13-O-18) = 29 +/- 6 ps. The spectral resolution in the frequency-domain experiment goes as far as the limit imposed by the natural lifetime; Q-branch lines, or f-parity components of the heavier isotopes, are resolved for the first time. Highly accurate transition frequencies are determined in a molecular beam experiment using comparison and interpolation with a saturated iodine reference standard. The results reveal a number of perturbations and predissociation mechanisms, displaying a high degree of complexity in the energetic region of the 4p Rydberg states of CO with strong isotopic effects. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 4. |
- Sprengers, JP, et al.
(author)
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Lifetime and predissociation yield of N-14(2) b (1)Pi(u)(v=1)
- 2004
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:19, s. 8973-8978
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Journal article (peer-reviewed)abstract
- The lifetime of the b (1)Pi(u)(v=1) state in N-14(2) has been determined experimentally using a laser-based pump-probe scheme and an exceptionally long lifetime of 2.61 ns was found. Semiempirical close-coupling calculations of the radiative lifetime, which include Rydberg-valence interactions in the singlet manifold, are consistent with this large value, giving a value of 3.61 ns and suggesting a predissociation yield of similar to28% for this level of the b state. (C) 2004 American Institute of Physics.
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| 5. |
- Sprengers, JP, et al.
(author)
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Pump-probe lifetime measurements on singlet ungerade states in molecular nitrogen
- 2004
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In: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 389:4-6, s. 348-351
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Journal article (peer-reviewed)abstract
- Excited-state lifetimes for a number of vibronic states of (1)Pi(u) symmetry in molecular nitrogen have been determined experimentally in a laser-based pump-probe scheme using a coherent and tunable extreme ultraviolet source based on harmonic generation. States investigated in N-14(2) were b(1)Pi(u)(v = 6-9), of valence character, and c(3)(1)Pi(u)(v = 1) and o(3)(1)Pi(u)(v = 1), of Rydberg character. In the case of b(1)Pi(u)(v = 7) and c(3)(1)Pi(u)(v = 1), rotationally dependent predissociation was observed. States studied in N-15(2) were b(1)Pi(u)(v = 5) and c(3)(1)Pi(u)(v = 1); in addition, lifetimes of the c(4)'Sigma(u)(+)(v = 0,1) and b'(1)Sigma(u)(+)(v = 1) states were determined. The lifetimes show a dependence on the vibrational quantum number and isotope. (C) 2004 Elsevier B.V. All rights reserved.
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