Energy distributions of emitted ion fragments following C(1<i>s</i>) excitations in CO

Erman, P.; Karawajczyk, A.; Köble, U; Rachlew-Källne, E.; Ky, Franzén

doi:10.1103/physreva.53.1407

“…The spectator decay model does not predict variations in the decay path of various Rydberg levels and, therefore, up to the validity of this approximation, no dependence of the fragmentation processes on the doorway state is expected. Nevertheless, a violation of this picture has been shown for the CO molecule for which reversed vibrational intensities in the CO + ion 0953-4075/96/081501+13$19.50 c 1996 IOP Publishing Ltd yield (Saito et al 1995) and surprising differences in the kinetic energy distributions (Erman et al 1995a) (KEDs) in the Rydberg series region have recently been reported.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation processes of the core-excited NO molecule

Erman

¹

,

Hatherly

²

,

Karawajczyk

³

et al. 1996

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

Ionization and fragmentation processes of the NO molecule following the excitation of the nitrogen 1s electron have been studied by means of high-resolution mass-selective ionyield measurements. The yields of N + , O + and NO + ions acquired with a quadrupole mass spectrometer (QMS) and a linear time-of-flight spectrometer (TOF) show surprising differences at the N(1s −1 ) threshold region suggesting the selective attachment of the excited core electron to the N + centre during the dissociation of the NO + ion. The fragmentation branching ratios corrected for the angular and kinetic energy effects are presented. The kinetic energy distributions of the N + and O + fragments have been extracted for a number of Rydberg states manifesting a significant dependence on l quantum number and energy of the primary excited Rydberg level. The lifetime of the core-excited N(1s −1 ) state has been found from the shape of the low kinetic energy electron spectra acquired above the 1 and 3 thresholds.

show abstract

“…Therefore, the de-excitation photoelectron spectra may exhibit deviations from the regular Franck-Condon behaviour. The role of this effect is expected to be small in the dissociation processes due to a large number of possible final channels as already reported for the CO (Saito et al 1995, Erman et al 1995a and N 2 molecules.…”

Section: Direct Measurementsmentioning

confidence: 53%

“…Since the β parameters for a number of states are known (Kosugi et al 1992) the KEDs may be derived from the spectra. The analysis procedure has been described elsewhere (Erman et al 1995a). Briefly, approximating the kinetic energy distribution with a continuous function k(v) and denoting the angular orientation of the dissociating molecules convoluted with the instrumental function as P (θ, v), the formula for the signal written for the velocity coordinates and corrected for the process of direct ionization of valence electrons reads (cos(θ ) = v /v):…”

Section: Kinetic Energy Distributionsmentioning

confidence: 99%

“…The spectator decay model does not predict variations in the decay path of various Rydberg levels and, therefore, up to the validity of this approximation, no dependence of the fragmentation processes on the doorway state is expected. Nevertheless, a violation of this picture has been shown for the CO molecule for which reversed vibrational intensities in the CO + ion yield (Saito et al 1995) and surprising differences in the kinetic energy distributions (Erman et al 1995a) (KEDs) in the Rydberg series region have recently been reported.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Untitled

Kardashëv

¹

,

Птускин

²

,

Belyavskiǐ

³

et al. 2007

PHYS-USP

5

0

View full text Add to dashboard Cite

Ionization and fragmentation processes of the NO molecule following the excitation of the nitrogen 1s electron have been studied by means of high-resolution mass-selective ionyield measurements. The yields of N + , O + and NO + ions acquired with a quadrupole mass spectrometer (QMS) and a linear time-of-flight spectrometer (TOF) show surprising differences at the N(1s −1 ) threshold region suggesting the selective attachment of the excited core electron to the N + centre during the dissociation of the NO + ion. The fragmentation branching ratios corrected for the angular and kinetic energy effects are presented. The kinetic energy distributions of the N + and O + fragments have been extracted for a number of Rydberg states manifesting a significant dependence on l quantum number and energy of the primary excited Rydberg level. The lifetime of the core-excited N(1s −1 ) state has been found from the shape of the low kinetic energy electron spectra acquired above the 1 and 3 thresholds.

show abstract

“…The CO molecule was chosen because its electronic spectroscopy and core level photofragmentation have been studied extensively, and because there have been several previous studies of the core level photofragmentation yields claiming quantitative results (6,7). Photoionization mass spectroscopy (6)(7)(8)(9)(10)(11)(12)(13)(14)(15), photoelectron spectroscopy (16,17), electron-ion coincidence spectroscopy (18,19), and electron energy loss spectroscopy (20-24) measurements on CO were performed. The results are compared to an early time-of-flight photoionization mass spectrometry study, in which a very short extraction pulse was used to improve quantitative collection (6), and to (e,e + ion) coincidence measurements (7) simulating photoionization, which are generally accepted to produce branching ratios free from kinetic energy distortion.…”

Section: Introductionmentioning

confidence: 99%

Quantitative oscillator strengths for ionic fragmentation of C 1s and O 1s excited CO

Guerra¹,

Maciel²,

Turci³

et al. 2004

View full text Add to dashboard Cite

Ionic photofragmentation of carbon monoxide following carbon 1s and oxygen 1s excitation has been measured quantitatively with tuned synchrotron light and time-of-flight mass spectrometry using a Wiley-McLaren apparatus modified with an additional ion lens for improved quantitative performance. The sensitivity of the apparatus to kinetic energy and angular distribution effects has been characterized for selected lens settings through ion trajectory simulations and experimental measurements. Three distinct modes of the added lens have been identified (focus, defocus, and maximum). The focus mode has the least sensitivity to details of the angular and ion kinetic energy distribution and, therefore, is the best mode for measuring quantitative partial ion and ion-pair yields. The defocus mode has the most sensitivity to angular and kinetic energy distributions and, therefore, is the mode that provides the most information about the kinematics of photofragmentation. Branching ratios for ion and ion-pair production in all positive ion fragmentation channels were recorded from 280 to 330 eV (C 1s) and from 520 to 570 eV (O 1s) in the "focus" mode. Quantitative oscillator strengths were derived by combining these branching ratios with absolute total ion yield spectra. The results are compared to literature values.

show abstract

Energy distributions of emitted ion fragments following C(1s) excitations in CO

Cited by 8 publications

References 13 publications

Fragmentation processes of the core-excited NO molecule

Fragmentation processes of the core-excited NO molecule

Untitled

Quantitative oscillator strengths for ionic fragmentation of C 1s and O 1s excited CO

Contact Info

Product

Resources

About