Measurement of hyperfine structure within the 6P3/2 excited state of 115In

Using a two-step, two-color laser spectroscopy technique, we have completed a measurement of the hyperfine structure within the (5s(2)6p) P-2(3/2) excited state in In-115 (I=9/2). A frequency stabilized GaN diode laser at 410 nm is locked to the 5P(1/2)-> 6S(1/2) ground-state transition and a second 1291 nm diode laser is scanned over the 6S(1/2)-> 6P(3/2) transition to produce hyperfine spectra for the 6P(3/2)(F=3,4,5,6) manifold. We find the hyperfine splittings of consecutive sublevels to be as follows: Delta nu(4-3)=275.25(42) MHz, Delta nu(5-4)=384.05(71) MHz, and Delta nu(6-5)=517.48(44) MHz. The magnetic dipole, electric quadrupole, and magnetic octupole hyperfine coupling constants derived from these three splittings are, respectively, a=79.33(7) MHz, b=62.5(5) MHz, and c=-0.04(4) MHz. The measured value of the dipole constant, a, agrees to within 2% with a recent theoretical prediction.