Lyman and Balmer emission following core excitations in methane and ammonia molecules
2007 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, no 8, 1489-1500 p.Article in journal (Refereed) Published
The intensities of hydrogen Lyman-alpha and Balmer series emission lines as a result of photoexcitation of free CH4 and NH3 molecules at the C 1s and N 1s edges have been measured. For methane, the total fluorescence yield in the visible region ( 300 - 650 nm) was also recorded. Excitation functions of the Balmer lines show relative intensity enhancement of Balmer-beta emission in comparison with Balmer-alpha at higher core- to- Rydberg excitations. The Lyman-alpha emission intensity, in general, follows the relations observed in the corresponding total ion yield measurements. Additionally, the Balmer-gamma and -delta yields were measured for ammonia molecules and they show intensity maxima at photon energies shifted closer to the N 1s threshold than Balmer-alpha and -beta. A quantum defect analysis is performed to find out which core excitations are responsible for this enhanced intensity. Dissociation pathways leading to the emission in H atoms are discussed.
Place, publisher, year, edition, pages
2007. Vol. 40, no 8, 1489-1500 p.
Ammonia, Dissociation, Fluorescence, Methane, Photons, Rydberg states, Balmer series emission lines, Core excitations, Photon energies, Quantum defect analysis, Rydberg excitations
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:kth:diva-7999DOI: 10.1088/0953-4075/40/8/003ISI: 000246010300004ScopusID: 2-s2.0-34247098021OAI: oai:DiVA.org:kth-7999DiVA: diva2:13201
QC 201009162008-02-202008-02-202010-11-17Bibliographically approved