Stark broadening data for many transitions of
many atoms and ions are needed
for diagnosis of laboratory and astrophysical plasmas. As an example, data
for more than 106 transitions, including line-profile parameters, are
needed for the calculation of stellar opacities (Seaton 1988).
With the development of space-borne spectroscopy, interest increases even
more for a large number of spectral line profile parameters. For example,
Leckrone et al. (1993) stated that with the Goddard High
Resolution Spectrograph (GHRS) on Hubble Space Telescope they "have
doubled the number of heavy elements (
) for which
abundances in 
Lupi can be estimated, compared to ground-based data
alone". Cardelli et al. (1991) have used the GHRS for
investigation of spectra of the interstellar medium, which more accurately
represents the pre-stellar material from which the Ap and Bp stars (where
Stark broadening data are of interest) are formed (Leckrone et al.
1993). For the first time, they have begun to detect elements such
as krypton and germanium.
Stark broadening for Kr II lines has additional theoretical interest for the investigation of regularities and systematic trends for singly-charged noble gas ions (e.g. Dimitrijevic & Popovic 1989; Di Rocco 1990; Puric et al. 1991; Bertuccelli & Di Rocco 1993). Stark broadening data for Xe II, which is homologous with Kr II, have been published recently (Popovic & Dimitrijevic 1996a). A consistent set of Stark broadening data for Kr II and Xe II enables the investigation and testing of regularities in the case of homologous atoms, as well as Stark width estimates for homologous sequences for noble gas ions.
Stark broadening of Kr II lines
have been considered experimentally (see e.g.
Brandt et al. 1981;
Pittman & Konjevic 1986; Vitel
& Skowronek 1987; Uzelac & Konjevic 1989;
Lesage et al. 1989; Bertuccelli & Di Rocco
1991) and theoretically (see e.g. Bertuccelli & Di Rocco
1993). Bertuccelli & Di Rocco (1993) have calculated
Kr II Stark widths for several lines
by using analytical expressions for the cross sections and rate
coefficients based on the Born approximation, with and without the empirical
modification for the collision strength suggested by Robb
and with the help of a semiempirical method (Griem 1968).
Estimates also exist based on the dependence on atomic number and the upper
level ionization potential, established from the consideration of
regularities (Di Rocco 1990; Puric et al.
1991; Bertuccelli & Di Rocco 1991, 1993). Here we
present Stark widths for 37 spectral lines from the 
transition array of singly-charged krypton, calculated by using a modified
semiempirical approach (Dimitrijevic & Konjevic 1980;
Dimitrijevic & Krsljanin 1986). Due to the complexity
of the Kr II spectrum, calculations were performed as in Popovic &
Dimitrijevic (1996b). Our results for Stark widths and shifts
are compared with the available experimental and theoretical data.