Lifetime‐Measurements of Selectively Excited Molecular Levels

Abstract

Den Annolen, der Ph?jsik zurn 200. Geburtstag gewidmet.A h s t ract. X synchroncously pumped modc-locked cavitj -dumped dye laser, which delivers ric.arly l!'i,riricr-limited output pril.ues with 20 W peak power, 600 ps pulsewidth and 1.5 GHz spectr;iI b:intlwidth is used to populirtc selected rovibronic levels in excited electronic states of alkali moleculcs.The I;mr induccrl fluorescence is filtered through a monochromator and the lifetimes of individunl rovibronic lcvcls nro determined N ith the singlo photon delayed coincidence technique. The influenco of tlift'crcnt perturbations on the lifctinies is investigated and discussed.Lcberisdaiieriiiessanaen an selektiv angeregten Molckiilniveaus .Inha1 tsii borsicht. Mit eincm synchron gepumpten modengekoppelten Farbstoffliiser, der fast Foiiric.rbegrc,nztc Piilso mit 20 W Spitzenleistnng, SOU PR Dnuer und 1.5 CHz spektraler Bmdbrcite licfert. werdcn einzelne Sch~~ingtings-Rotntioncl-Pu'ivciiiis in elektronisch nngeregtcn Zustlnden von Alkali-Dimercn selektiv bevolkert und ihre Imbensdiiuern mit Hilfc der Phobncnziihltechnik mit. vcrziigcrt,er Koinzidenz gemessen. Der EinfluB vcrschicdener molekularer Storungen (PrYdissoziation, SI'in-B;ilin-Roppliing) uuf die Lebensdauern inclividrieller Sivcaus wird rrntersiictit rind clir diirtcus gewonnencn Erkenntnisse dislrutiert.

A comment on Hönl-London factors

“…When the calculated lifetimes are divided by 4 to convert to the present Hö nl-London factors, it is seen that there is good agreement with the lifetimes measured by Bieniak et al [18]. [18]. Table 2 Hö nl-London factors for lines of low-K emission bands Transition R-line S J 0 K 0 0 ;J 00 K 00 00 Q-line S J 0 K 0 0 ;J 00 K 00 00 P-line S J 0 K 0 0 ;J 00 K 00 00 Sum over J 00 and 00 P j 00 00 S J 0 K 0 0 ;J 00 K 00 00 1 R ± fi 1 R ± J 0 0 J 0 + 1 2J 0 + 1 1 R ± fi 1 P J 0 À1 2 J 0 + 1 J 0 + 2 2(2J 0 + 1) 1 P (e) fi 1 R + J 0 + 1 0 J 0 2J 0 + 1 1 P (f) fi 1 R + 0 2 J 0 + 1 0 2J 0 + 1 1 P (e) fi 1 R À 0 2 J 0 + 1 0 2J 0 + 1 1 P (f) fi 1 R À J 0 + 1 0 J 0 2J 0 + 1 1 P (e) fi 1 P…”

“…The lifetime is determined by emission to the X 1 R þ g state, the RKR potentials are from [15] and [16], and the transition-moment function from [17]. When the calculated lifetimes are divided by 4 to convert to the present Hö nl-London factors, it is seen that there is good agreement with the lifetimes measured by Bieniak et al [18]. [18].…”

Spectral and Time-Resolved Studies of Green Cs2Fluorescence

“…The lifetimes of such perturbed levels can, in general, be shortened or prolonged [29][30][31][32] as relative to those of unperturbed levels. For example in multiexponential decays of the C(2) 1 u state of Cs 2 , the two shorter lifetimes were attributed to levels predissociating via a repulsive triplet state [29].…”

“…From lifetimes for C(2)1Πu (red excitation) reported by Kato et al [29] one can deduce: Γp 260 s-1 ass Pp = 1930 µs-1 , for weaker and stronger predissociated levels, respectively. Bieniak et al [30] reported Γp = 45=323μis-1 for D(2) 1E,1 (υ' = 43, J' = 92=129) levels (yellow excitation) assuming the unperturbed lifetime of 18 ns.…”

Calculation of radiative parameters for the $$ {A^1}\sum\nolimits_u^{+} {{X^1}} \sum\nolimits_g^{+} {} $$ -transition of cesium dimer

“…The vibrational and rotational molecular constants required for constructing the potential curves of X 1 Σ g + -and A 1 Σ u + -states were taken from the literature [19,20]. Radiative lifetimes of Cs 2 were measured for electronic states C [21][22][23]. Construction of Potential Curves.…”