  Laser spectroscopy of short-lived radium isotopes in a linear Paul trap has
been performed. The isotope shifts of the $6d\,^2$D$_{3/2}\,$ -
$7p\,^2$P$_{1/2}\,$ transition in $^{209-214}$Ra$^+$ were measured, which are
sensitive to the short range part of the atomic wavefunctions. The results are
essential experimental input for improving the precision of atomic structure
calculation. This is indispensable for parity violation in Ra$^+$ aiming at the
determination of the weak mixing angle.
