Abstract. Lifetimes of Rydberg states of the triplet-series 5s ns 3S 1 with n= 19-23, 35 and 5s nd 3D 3 with n= 18-20, 23-28 in the spectrum of neutral strontium have been determined. Observation of the exponential decay after excitation by a pulsed laser in a fast atomic beam and subsequent state-selective field ionization was employed. The lifetimes of the states of the 3Sl-series show the expected n* 3 dependence on the effective principal quantum number, while the 3D3-series is disturbed by configuration mixing. Furthermore, state re-populations induced by black-body radiation have been observed.
High-resolution state-selected ion-molecule reaction studies using pulsed field ionization photoelectronsecondary ion coincidence method Rev. Sci. Instrum. 74, 4096 (2003); 10.1063/1.1599071Selective field ionization of high Rydberg states: Application to zero-kinetic-energy photoelectron spectroscopy Dissociation of stateselected complex ions studied by massselective pulsed field threshold ionization spectroscopy J. Chem. Phys. 97, 5923 (1992); 10.1063/1.463754The first ionization potential of zirconium atoms determined by two laser, fieldionization spectroscopy of high lying Rydberg series
An experimental system has been developed wherein a pulsed laser beam photofragments molecules of a gaseous sample introduced into a vacuum chamber. Fluorescence of the fragments so produced is observed. Studies of emission by photoproducts of the excimer laser photolysis of nitromethane at 193 nm are reported here. The principal fragment emission occurs at 431 nm, due to the CH A2Δ-X2II transition. A limit of detection for nitromethane of 1.6 × 108 molecules is reported, corresponding to an interrogated sample volume of 0.0375 cm3 and a chamber pressure of 1.3 × 10−7 Torr (i.e., a concentration of 4.2 × 109 molecules/cm3). The linear dynamic range extends over 3.5 decades in nitromethane pressure. The fragment fluorescence measurements can be made with excellent precision (relative standard deviation of less than 4%). The CH fragment fluorescence signal is linear in the first power of laser fluence over the range of 60 to 135 mJ/pulse (0.8–1.8 J/cm2).
The use of molecular fragmentation for fluorometric detection and quantification of nonfluorescent organic and organometallic compounds is described. The measurements are based on the emissive characteristics of many small molecular fragments (OH, CN, CH, etc.). Fragmentation is induced by 100-eV electrons or 193-nm photons. Limits of detection, linearity, reproducibility, and range of applicability of the measurements are discussed. The merits of laser photolysis and electron impact as techniques for generating fluorescent fragments from nonfluorescent analyte molecules are compared.
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