LINE SHAPE PARAMETERS OF WATER VAPOR TRANSITIONS IN THE 3645-3975 cm−1 REGION

A Bruker IFS 120HR Fourier transform spectrometer (FTS) at the Pacific Northwest National Laboratory (PNNL)_x000d_ in Richland, Washington was used to record a series of spectra in the regions of the $nu_1$ and $nu_3$ bands_x000d_ of H$_2$O. The samples included low pressures of pure H$_2$O as well as H$_2$O broadened by air at different pressures, temperatures and volume mixing ratios. We fit simultaneously 16 high-resolution (0.008 cm$^{-1}$), high S/N ratio absorption spectra recorded at 268, 296 and 353 K (L=19.95 cm), employing a multispectrum fitting _x000d_ techniquefootnote{D.~C.~Benner, C.~P.~Rinsland, V.~Malathy Devi, M.~A.~H.~Smith, D.~Atkins, textit{JQSRT} _x000d_ textbf{53} (1995) 705-721.} to retrieve accurate line positions, relative intensities, _x000d_ Lorentz air-broadened half-width and pressure-shift coefficients and their temperature dependences for _x000d_ more than 220 H$_2$O transitions. Self-broadened half-width and self-shift coefficients were measured _x000d_ for over 100 transitions. For select sets of transition pairs for the H$_2$O-air system we determined _x000d_ collisional line mixing coefficients via the off-diagonal relaxation matrix element _x000d_ formalismfootnote{A.~Levy, N.~Lacome, C.~Chackerian, Collisional line mixing, in textit{Spectroscopy of _x000d_ the Earth$^prime$s Atmosphere and Interstellar Medium}, Academic Press, Inc., Boston (1992) 261-337.}, _x000d_ and we also measured speed dependence parameters for 85 transitions. Modified Complex Robert Bonamy (MCRB) _x000d_ calculations of the half-widths, line shifts, and temperature dependences were made for _x000d_ self-, N$_2$-, O$_2$-, and air-broadening. The measurements and calculations are compared with each _x000d_ other and with similar parameters reported in the literature