Journal ArticleDOI
Long Optical Paths of Large Aperture
TLDR
In this article, an absorption cell is described, in which the light traverses a small volume a large and arbitrarily variable number of times, and the angular aperture of the mirrors is not occulted either on or off the optical axis, and can be used for observing spectra that are very weak, or that belong to high boiling point compounds or to compounds obtainable only in very low concentrations.Abstract:
THE measurement of the vapor phase spectra T of compounds having high boiling points presents an experimental problem that may be solved either by heating the absorption cells or by making them very long. In the infra-red region radiation from the hot gases in heated cells decreases the accuracy of absorption measurements. If only a small amount of sample is available, the only possibility is to use an optical system in which the radiation goes back and forth through the same volume a large number of times. Several designs for such systems have been published recently1' 2 but none of them permits the use of large angular apertures at points off the optic axis. In this paper an absorption cell is described in which the light traverses a small volume a large and arbitrarily variable number of times, and in which the angular aperture of the mirrors is not occulted either on or off the optical axis. The design gives very high light transmission and can be used for observing spectra that are very weak, or that belong to high boiling point compounds or to compounds obtainable only in very low concentrations. It can be used for any liquids or gases that do not injure the mirror surfaces, with which they are directly in contact. The essential parts of the equipment are three spherical, concave mirrors that all have the same radius of curvature. These are set up as shown in Fig. 1 with two mirrors A and A' close together at one end of the absorption cell, and the third mirror B at the other end. The centers of curvature of A and A' are on the front surface of B, and the center of curvature of B is halfway between A and A'. This arrangement establishes a system of conjugate foci on the reflecting surfaces of the mirrors, by which all the light leaving any point on A is brought to a focus by B at the corresponding point on A', and all the light leaving this point on A' is focused back again to theread more
Citations
More filters
Journal ArticleDOI
Cavity ring‐down optical spectrometer for absorption measurements using pulsed laser sources
TL;DR: In this paper, the authors have developed a technique which allows optical absorption measurements to be made using a pulsed light source and offers a sensitivity significantly greater than that attained using stabilized continuous light sources.
Journal ArticleDOI
Optical gas sensing: a review
Jane Hodgkinson,Ralph P. Tatam +1 more
TL;DR: In this article, the authors present the basis for each technique, recent developments in methods and performance limitations, and present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.
Journal ArticleDOI
Measurements of molecular absorption spectra with the SCIAMACHY pre-flight model: instrument characterization and reference data for atmospheric remote-sensing in the 230–2380 nm region
K Bogumil,Johannes Orphal,T Homann,S. Voigt,Peter Spietz,Oliver C. Fleischmann,A Vogel,M Hartmann,H Kromminga,Heinrich Bovensmann,Johannes Frerick,John P. Burrows +11 more
TL;DR: In this paper, the authors used the scanning imaging absorption spectrometer for atmospheric chartography (SCIAMACHY) pre-flight model satellite spectrometers to measure the gas-phase absorption spectra of the most important atmospheric trace gases (O3, NO2, SO2, O2, H2O, CO, CO2, CH4, and N2O) in the 230-2380 nm range at medium spectral resolution and at several temperatures between 203 and 293
Journal ArticleDOI
The heterogeneous hydrolysis of NO2 in laboratory systems and in outdoor and indoor atmospheres: An integrated mechanism
TL;DR: In this article, the authors proposed a new reaction mechanism in which they hypothesize that the symmetric form of the NO2 dimer, N2O4, is taken up on the surface and isomerizes to the asymmetric form, ONONO2.
Journal ArticleDOI
Quantum cascade lasers in chemical physics
Robert F. Curl,Federico Capasso,Claire F. Gmachl,Anatoliy A. Kosterev,Barry McManus,Rafal Lewicki,Michael Pusharsky,Gerard Wysocki,Frank K. Tittel +8 more
TL;DR: In the short space of 15 years since their first demonstration, quantum cascade lasers have become the most useful sources of tunable mid-infrared laser radiation as discussed by the authors, and the potential application of quantum cascade laser in other areas of chemical physics such as research on helium droplets, in population pumping and in matrix isolation infrared photochemistry.
References
More filters
Related Papers (5)
Off-Axis Paths in Spherical Mirror Interferometers
Astigmatic mirror multipass absorption cells for long-path-length spectroscopy
Cavity ring‐down optical spectrometer for absorption measurements using pulsed laser sources
The HITRAN 2008 molecular spectroscopic database
Laurence S. Rothman,Iouli E. Gordon,Yurii L. Babikov,A. Barbe,D. Chris Benner,Peter F. Bernath,Manfred Birk,Luca Bizzocchi,Vincent Boudon,Linda R. Brown,Alain Campargue,Kelly Chance,Edward A. Cohen,L. H. Coudert,V. M. Devi,Brian J. Drouin,André Fayt,Jean-Marie Flaud,Robert R. Gamache,Jeremy J. Harrison,Jean-Michel Hartmann,Christian Hill,Joseph T. Hodges,D. Jacquemart,Antoine Jolly,Julien Lamouroux,R. J. Le Roy,Gang Li,David A. Long,O.M. Lyulin,C.J. Mackie,Steven T. Massie,Semen Mikhailenko,Holger S. P. Müller,Olga V. Naumenko,Andrei Nikitin,Johannes Orphal,V.I. Perevalov,Agnes Perrin,E. R. Polovtseva,Charlotte Richard,Mary Ann H. Smith,Evgeniya Starikova,Keeyoon Sung,S.A. Tashkun,Jonathan Tennyson,Geoff Toon,Vl.G. Tyuterev,G. Wagner +48 more