Abstract
An experimental study of the two-photon spectra of high membersof the Sr I 5snd 1,3D2 Rydberg series isdescribed. We use transverse excitation of an atomic beam witha narrow-bandwidth tuneable dye laser within a heat pipeequipped for field ionization detection. The presence of weakcollisions has revealed several anomalies. Strong spin-orbitinteraction and the breakdown of parity and selection rulescombined with `l' mixing are observed. The breakdown is dueto the Stark field present in the interaction region.Single-photon transitions originating from the5snp 1P1 and 5snp3PJ statespopulated by electron impact excitations are also observed.They create highly compact doubly excited 4d23PJ, 5p21D2 and4d5p 3PJ states, which act as dominant intruders inthe observed spectrum. Such states with highly localizedorbitals survive collision and field effects, whereas Rydbergstates are highly sensitive to external perturbations. Also, wehave observed l-changing collisional processes like Ar + Sr (5s}nd 1,3D2) → Sr (5snl,l⩾ 3).Several members of a new series which begin to appear at largen are observed and are tentatively designated as the5snf 1F3 Rydberg series. Furthermore, we haveobserved and identified several members of the Sr I5snp 1P1 and 5snp 3P2 Rydbergseries by two-photon absorption from the ground state. They areexcited via the breakdown of parity and other selection rules,owing to the presence of external fields. New values of energylevels of the Sr I 5snd 1,3D2 Rydberg series arepresented: n=25-73 for singlet and n=25-47 for tripletmembers, obtained from two-photon spectra. Comparison of thesevalues with those given by other authors who used differentexcitation schemes shows good agreement. The spectrum offluorescence emission from a low-pressure discharge around thefield ionization probe was obtained using amonochromator-photomultiplier detection system. The emissionlines confirm the collisional excitations observed in thespectra of the Rydberg series. An energy level diagramsummarizing the various transitions observed in our study isalso presented.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Physics B: Atomic, Molecular and Optical Physics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
