Spin-forbidden c3(SIGMA1)+ -X1SIGMA+ band system of YF

摘要

Optical spectra of jet-cooled diatomic YF have been recorded using resonant two-photon ionization spectroscopy.A vibrational progression corresponding to the c3(SIGMA1)+<- X 1SIGMA+ system has been identified.The vibrational frequency(omega_e)' and anharmonicity(omega_e)' of the c 3SIGMA+ state are 546.70 and 2.45 cm~(-1),respectively.The 0-0,1-0,and 2-0 bands of the c 3(SIGMA1)+ <-X 1SIGMA+ system were rotationally resolved and analyzed,allowing the upsilon'=0,1,and 2 levels of the c 3(SIGMA1)+ substate to be characterized.From these studies,B'_e=0.269 81(3)cm"1,alpha'_e=0.001 72(3)cm~(-1),and r'_e=1.9979(1)A were obtained(1 sigma error limits).For these levels the spin-spin coupling constant lambda_(upsilon)is identical within experimental error,as lambda=-22.5 cm~(-1).The spin-forbidden c 3(SIGMA1)+ <- X 1SIGMA+ transition is made allowed by spin-orbit interaction between the c 3(SIGMA1)+ and the B 1II states.Excited state lifetimes of the c 3(SIGMA1)+ and the B 1II states have been measured as 7.11(41)and 0.133(15)mu s,respectively.A spin-orbit analysis shows that the c 3(SIGMA1)+ state is contaminated with 2% B lII character,which is approximately sufficient to explain the 7 mu s lifetime of the c 3(SIGMA1)+ state.