Submillimeter-Wave Spectra of HCl and HBr

The $J=0\mathrm{}\to 1$ transitions of HCl and HBr have been measured in the wavelength regions of 0.59 and 0.48 mm, respectively. These measurements led to the following values of molecular constants: for H${\mathrm{Cl}}^{35}$, ${\nu }_0=625\mathrm{}919.24\pm 0.52$ Mc/sec, $eQq=63.0\mathrm{}\pm 2.8$ Mc/sec, $C_I\approx 0$, $B_0=312\mathrm{}991.30\pm 0.26$ Mc/sec, $B_e=317\mathrm{}587$ Mc/sec, $r_0={1.2838}_7$ Å, $r_e={1.2745}_5$ Å; for H${\mathrm{Br}}^{79}$, ${\nu }_0=500\mathrm{}675.24\pm 0.52$ Mc/sec, $eQq=535.4\mathrm{}\pm 1.4$ Mc/sec, $C_I=0.29\mathrm{}\pm 0.20$ Mc/sec, $B_0=250\mathrm{}360.78\pm 0.13$ Mc/sec, $B_e=253\mathrm{}790$ Mc/sec, $r_0={1.4243}_9$ Å, $r_e={1.4146}_0$Å; and for H${\mathrm{Br}}^{81}$, ${\nu }_0=500\mathrm{}519.41\pm 0.26$ Mc/sec, $eQq=447.9\mathrm{}\pm 1.4$ Mc/sec, $C_I=0.31\mathrm{}\pm 0.20$ Mc/sec, $B_0=250\mathrm{}282.88\pm 0.13$ Mc/sec, $B_e=253\mathrm{}710$ Mc/sec, $r_0={1.4140}_2$ Å, $r_e={1.4146}_0$ Å.