Carbon dioxide laser absorption spectra and low ppb photoacoustic detection of hydrazine fuels

Loper, G. L.; Calloway, A. R.; Stamps, M. A.; Gelbwachs, Jerry A.

doi:10.1364/ao.19.002726

Cited by 28 publications

(1 citation statement)

References 18 publications

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“…Using such a mixing arrangement, we were able to prepare a given concentration level in a flow regime (flow rate 1 cm 3 s −1 ) and under atmospheric pressure, with methanol vapour as the testing gas. The CO 2 laser was tuned to the 9 P(34) CO 2 laser line (1033.488 cm −1 ), which corresponds to the fundamental CO stretching band of methanol, where the maximal absorption cross section is 72 × 10 −20 cm 2 (Loper et al, 1980).…”

Section: Methodsmentioning

confidence: 99%

Silicon micro-levers and a multilayer graphene membrane studied via laser photoacoustic detection

Zelinger

Janda

Suchánek

et al. 2015

J. Sens. Sens. Syst.

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Abstract. Laser photoacoustic spectroscopy (PAS) is a method that utilizes the sensing of the pressure waves that emerge upon the absorption of radiation by absorbing species. The use of the conventional electret microphone as a pressure sensor has already reached its limit, and a new type of microphone -an optical microphone -has been suggested to increase the sensitivity of this method. The movement of a micro-lever or a membrane is sensed via a reflected beam of light, which falls onto a position-sensing detector. The use of one micro-lever as a pressure sensor in the form of a silicon cantilever has already enhanced the sensitivity of laser PAS.Herein, we test two types of home-made sensing elements -four coupled silicon micro-levers and a multilayer graphene membrane -which have the potential to enhance this sensitivity further. Graphene sheets possess outstanding electromechanical properties and demonstrate impressive sensitivity as mass detectors. Their mechanical properties make them suitable for use as micro-/nano-levers or membranes, which could function as extremely sensitive pressure sensors.Graphene sheets were prepared from multilayer graphene through the micromechanical cleavage of basal plane highly ordered pyrolytic graphite. Multilayer graphene sheets (thickness ∼ 10 2 nm) were then mounted on an additional glass window in a cuvette for PAS. The movements of the sheets induced by acoustic waves were measured using an He-Ne laser beam reflected from the sheets onto a quadrant detector. A discretely tunable CO 2 laser was used as the source of radiation energy for the laser PAS experiments. Sensitivity testing of the investigated sensing elements was performed with the aid of concentration standards and a mixing arrangement in a flow regime. The combination of sensitive microphones and micromechanical/nanomechanical elements with laser techniques offers a method for the study and development of new, reliable and highly sensitive chemical sensing systems. To our knowledge, we have produced the first demonstration of the feasibility of using four coupled silicon micro-levers and graphene membranes in an optical microphone for PAS. Although the sensitivity thus far remains inferior to that of the commercial electret microphone (with an S/N ratio that is 5 times lower), further improvement is expected to be achieved by adjusting the micro-levers and membrane elements, the photoacoustic system and the position detector.

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Section: Methodsmentioning

confidence: 99%

Silicon micro-levers and a multilayer graphene membrane studied via laser photoacoustic detection

Zelinger

Janda

Suchánek

et al. 2015

J. Sens. Sens. Syst.

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Photoacoustic Spectroscopy in Trace Gas Monitoring

Harren

Mandon

Cristescu

2000

Encyclopedia of Analytical Chemistry

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Since ancient times people have searched for ways to understand processes occurring in the environment, atmosphere or living organisms. Study of the gaseous trace compounds present may shed new light on chemical reactions taking place in the atmosphere or biochemical reactions inside organisms such as plants, animals and human beings. This article presents photoacoustic spectroscopy as a sensitive, on‐line and noninvasive tool for monitoring the concentration of trace gases. Following a short introduction and a historic overview, attention is focused on the description of devices and equipment which determine the detection limits and selectivity. An overview is given of the current detection limits for photoacoustic detection. Applications are discussed with emphasis on environmental monitoring (in ambient air, car exhaust and stack gas emission), on medical applications and on biological applications (in postharvest physiology, plant physiology, microbiology and entomology).

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