Multiple Reflection Raman Tubes for Gases

Vibrational relaxation of NO(=1–3) and NO2(0,0,1) with atmospheric gases

“…In the Ðrst, UV radiation was multipassed through the reaction vessel and IR radiation collected with Welch cell optics. 16 Although this allowed low signal levels to be processed, it su †ered from the disadvantage that in some cases long pathlengths of the emitting radiation led to considerable self absorption (particularly noticeable for emission from the (0,0,1) level of Accord-NO 2…”

AN IMPROVED TECHNIQUE FOR THE OBSERVATION OF INFRARED CHEMILUMINESCENCE: RESOLVED INFRARED EMISSION OF OH ARISING FROM THE SYSTEM H + O2

“…T h e mirror systeill consisted of four concave inirrors, all four having very closely matched radii of curvature; the system was identical with t h a t suggested by IVelsh and co-\vorlcers (13,14) for use in high-resolution Raman spectroscopy. T h e radius of curvature of the mirrors in our system lvas 50.094 cm, diaineter 14 cm, and average tl~iclcness 1.5 cm.…”

“…T o facilitate the alignment of the spectrometer to the reaction cell, and the alignment of the lllultiple reflection systenl within the reaction cell, a light bulb was mounted permanently inside the spectrometer on a solenoid arm so that it could be moved into a position behind the foreprism monochroineter slit by closing a switch. This made possible rapid checks of alignment during the course of an experiment; a t the same time a check could be made for deterioration of the mirrors, by counting the number of images formed a t the front nlirrors by the multiple cones of light within the cell (13,14).…”

Photodissociation dynamics of dicyclopropyl ketone at 193 nm: Isomerization of the cyclopropyl ligand

“…24 These multipass collection optics gather light from the relatively large excitation volume with high numerical aperture and focus this light to a small area ͑ϳ0.8 mm 2 ͒ needed for fast infrared detectors. The emission exits the flow cell through a KBr window, is collimated and refocused by a pair of 90 degree off-axis paraboloid mirrors, and is spectrally filtered using combinations of long-and short-wave pass filters.…”