L . B . Lapson

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A simple and easy to use method that allows high-finesse optical cavities to be used as absorption cells for spectroscopic purposes is presented. This method introduces a single-mode continuous-wave laser into the cavity by use of an off-axis cavity alignment geometry to eliminate systematically the resonances commonly associated with optical cavities,(More)
We describe here the Harvard integrated cavity output spectroscopy (ICOS) isotope instrument, a mid-IR infrared spectrometer using ICOS to make in situ measurements of the primary isotopologues of water vapor (H(2)O, HDO, and H(2) (18)O) in the upper troposphere and lower stratosphere (UTLS). The long path length provided by ICOS provides the sensitivity(More)
The odd-hydrogen radicals OH and HO2 are central to most of the gas-phase chemical transformations that occur in the atmosphere. Of particular interest is the role that these species play in controlling the concentration of stratospheric ozone. This paper describes an instrument that measures both of these species at volume mixing ratios below one part in(More)
Although the ability of high finesse optical cavities to provide effective absorption path-lengths exceeding 10 km. has been known for quite some time, attempts to utilize this property for the purposes of high-resolution spectroscopy have often resulted in extremely complex experimental systems. Here, we demonstrate how off-axis optical paths through such(More)
The photoelectric yields of 2000-A thick samples of MgF(2) and LiF have been measured at wavelengths in the range 1216-461 A. Peak values of 43% and 34%, respectively, were obtained at wavelengths around 550 A at 45 degrees incidence. Coating the cathode of a channel electron multiplier with 3000 A of MgF(2) produced no significant deterioration in the(More)
The odd-hydrogen radicals OH and HO2 are central to most of the gas-phase chemical transformations that occur in the atmosphere. Of particular interest is the role that these species play in controlling the concentration of stratospheric ozone. This paper describes an instrument that measures both of these species at volume mixing ratios below one part in(More)
The procedures available for photometric calibration at extreme ultraviolet (EUV) wavelengths are outlined and the requirements for a secondary standard EUV photomultiplier defined. The performance of a number of commercially available channel electron multipliers over the 304-1350-A wavelength range is described and their suitability for use as secondary(More)
A:bstrac•. Simultaneous, in situ measurements of OH, :HOa, HaO, and O, from 37-23 km are reported, The par6fioning between OH and HOa and the total HO• concentm•:io.n are compared w•th expected steady-state values. The ratio of HOa to OH varies from less than 2 at 3õ km to .more than 3 at 25 km; in the lower stratosphere this ratio [s nearly a factor of two(More)
High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based(More)