PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HIGH GALACTIC LATITUDE MOLECULAR CLOUDS .2. HIGH-RESOLUTION SPECTROSCOPIC OBSERVATIONS OF NA-I, CA-II, CA-I, CH, AND CH+

High-resolution spectroscopic observations in the wavelengths of the atomic species Na I, Ca II, and Ca I and the molecular species CH and CH+ have been conducted toward stars behind a variety of high Galactic latitude molecular clouds (HLCs), and 17 new detections of molecular absorption are reported. For 13 regions, multiple detections of Na I absorption lines are used to map the spatial extent and possible dynamics of the HLCs, and to constrain the distance and velocities of the clouds more accurately. New and improved distance estimates are reported for several clouds, including the Ursa Major complex MBM 29-MBM 31 and MBM 151, which are found to be at 100 pc < d < 120 pc, and d < 50 pc, respectively. The detection of Na i absorption in a star with d < 50 pc toward MBM 151 appears to make MBM 151 the nearest molecular cloud yet identified, although substantial additional material appears to exist at 50 pc < d < 150 pc. A detection of molecular absorption of CH and CH+ toward the halo star HD 89688 is also presented, which may be sampling molecular material in the Galactic halo. For the sight lines with detected molecular absorption, a detailed analysis of the properties of the clouds is performed, by studying the ratios N(Na I)/N(Ca II), N(Ca I)/N(Ca II), and N(CH)/N(CH+) to detect the presence of shock-enhanced grain disruption, to measure the electron and cloud densities, and to help constrain models of photochemistry. The ratios of N(Na I)/N(H I) are also analyzed to derive the hydrogen number density n(H) for all the sight lines with Na I observations, using typical values for the depletion delta(Na) and the ionization state. The molecular hydrogen column density N(H-2) is derived from CH detections, and values or upper limits of N(H-2)/N(H I) are reported for 24 sight lines. Molecular hydrogen content and ionic ratios of the species CH and CH+ are used to determine whether the cloud molecular content is consistent with predictions of shock chemistry models. In most cases, the existing theoretical models are unable to produce the observed quantities of CH+ by an order of magnitude. The atomic and molecular line ratios observed toward the high Galactic latitude clouds are also compared with Galactic plane sight lines to determine whether some or all of the observed clouds are typical of Galactic molecular clouds, or whether instead they represent a distinct and unique population of molecular clouds. The HLCs are found to contain dense condensations with n(H) approximately 10(3) CM-3, with a high degree of spatial condensation along filamentary structures, many of which have derived sizes r < 0.5 pc and masses ranging from 0.03 to 140 M.. For a few of the sight lines with CH and CH+ detections, measurable CH and CH+ velocity offsets are found, and the values of N(Na I)/N(Ca II) argue for some shock disruption of the clouds. The high Galactic latitude clouds are found to have similar properties to diffuse molecular clouds in the Galactic plane, yet with enhanced molecular abundances per unit extinction and larger values of N(H-2)/N(H I) = 0.5 than in typical diffuse clouds. The enhanced density and molecular H-2 and CH content of the HLCs are also found to be outside the range of current shock chemistry and photochemistry models. The molecular detections appear toward the edges of dense HLC cloud cores, which are local peaks of 100 mum emission. The sizes, densities, and molecular content found for the HLCs are consistent with an interpretation of the HLC molecular cores as extremely compact structures of enhanced molecular content which may have evolved from larger H I shells.