Air monitoring

High Sensitivity, High Reliability Trace Gas Sensors using optical detection - C. Kumar N. Patel

Author: C. Kumar N. Patel on behalf of Pranalytica Inc

Free to read

This article has been unlocked and is ready to read.

Download

Pranalytica, Inc. located in Santa Monica, CA specializes in technology and products for ultra low level, high reliability detection of trace gases. Pranalytica uses tunable laser based photoacoustic spectroscopy (O-Nose™ Technology) for the detection of many molecular gases at ppb and sub-ppb levels without interference from other gases that may be present in the sampled gas. Pranalytica’s instruments are field proven, rugged and reliable; they are able to operate autonomously without operator intervention or assistance; they provide data on a continuous basis with a fresh measurement every 12 seconds and they can be interfaced with central data collection systems in using a broad variety of communication protocols.

Principle of photoacoustic spectroscopy can be understood through figure 1. The sample gas is illuminated by a radiation at frequency ν. When the frequency ν coincides with the absorption frequency of the target molecule, the photon can be absorbed by the molecule and the molecule is now excited to a higher state from which the molecule can relax back to the initial state by radiative or nonradiative mechanisms. Nonradiative relaxation converts the internal excitation energy of the molecule into translational energy and the molecular gas is now heated. If the incoming radiation is periodically interrupted, as shown in the figure, the gas is periodically heated. Such periodic heating is equivalent to periodic variation in the gas pressure. If the amplitude modulation occurs at an audio frequency, the resultant pressure fluctuations, sound, can be detected using a sensitive microphone as shown and the electrical signal corresponds to the rate at which the excited molecules decay back to their initial state. It is instructive to point out that

Free to read

This article has been unlocked and is ready to read.

Download


Digital Edition

AET 28.4 Oct/Nov 2024

November 2024

Gas Detection - Go from lagging to leading: why investment in gas detection makes sense Air Monitoring - Swirl and vortex meters will aid green hydrogen production - Beyond the Stack: Emi...

View all digital editions

Events

Abu Dhabi Sustainability Week

Jan 12 2025 Abu Dhabi, UAE

World Future Energy Summit

Jan 14 2025 Abu Dhabi, UAE

Clean Fuels Conference

Jan 20 2025 San Diego, CA, USA

Carrefour des Gestions Locales de L'eau

Jan 22 2025 Rennes, France

Safety, Health & Wellbeing LIVE

Jan 22 2025 Manchester, UK

View all events