Page 58 - Tunable Lasers Handbook

3 Tunable Excirner Lasers 39
transferred rapidly between the states and therefore the spectrum is not homoge-
neously broadened.
The 353-nm band emission comes primarily from the XeF (B, 1“ = 0) -+ XeF
(X. I]’’ = 3) transition. whereas the 351-nm band is composed of radiation from the
XeF (B, ?’ = 1) -+ XeF (X, Y’’ = 3) and XeF (B, 1,’ = 0) -+ XeF (X, Y”= 2) transi-
tions. Each vibrational transition has four rotational branches: Pe. Re. Pf. and Rf
where e andfrepresent spin “up” and spin ”down” for the transitions. Both bands
have considerable structure, which is attributed to overlapping rovibronic transi-
tions. As the temperature is increased. the spectra and efficiency of the 353-nrn

a

I I I I
351 .O 351 5 352.0 352 5 353 0 353.5
Wavelength (nrn)

I I I I 1 - I
351.0 351.5 352.0 352.5 353.0 353.5
Wavelength (nrn)
FIGURE 3 Fre2 running lasers spectrum of X2F (B+X transition) at (ai 300’K and (b) li@K
Inhomogeneous characteristics ar2 evident (from Harris et al. [34]i.