Home > Chemical > Technology > Molecular Spectroscopy > Photoacoustic Detection (PA)

Photoacoustic spectroscopy utilizes the principles of radiation absorption and the photoacoustics for molecular detection. Samples, which can be solids, semi-solids, liquids, or gases, are placed into a closed cell containing a non-absorbing gas.  The sample is then irradiated and energy absorbed by the solid is released when the surrounding gas molecules, which are heated by the solid, subsequently relax back to the initial vibrational state. The excess heat energy causes a change in the pressure of the gas cell. The pressure change results in an acoustic wave, which can be detected with a sound measuring device, such as a microphone or a piezoelectric sensor.  Visible and ultraviolet light may be used as radiation sources in PAS, but the most modern instrumentation relies on infrared radiation. Advantages of PA detectors include high sensitivity and stability, wide dynamic range, and quick response. The main disadvantage of PA detectors is poor specificity and susceptibility to interference. As a result, detectors using this technology are not recommended for screening of unknown samples.  PAS has been used in studies of biological systems, pharmaceutical analysis, nanoparticulate materials, and materials science.  PAS instruments are available in both benchtop and portable models.  The technique is mature, but seeing increased use with the inclusion of infrared radiation sources.  Commercial instruments are readily available.

Applied Nanotech, Inc. (1)
LumaSense Technologies, Inc. (2)
Pocket Size (1)
Person-Portable (1)
Benchtop/Fixed (1)
Commercially Available (2)
In Development (1)
Unit Cost
$20,000 - $50,000 (1)
N/A (2)
Sample Introduction
Vapor/Gas (3)
Sensitivity / Detection Limit
ppm (2)
ppb (1)

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Instrument (2)
Sensor (1)


4 (1)
9 (2)


<30 Lbs. (2)
<50 Lbs. (1)

Power Requirement

Lithium Battery (3)

Training Required

<1 day (1)
<1 week (2)

Response Time

Continuous (<30 seconds) (1)
<1 minute (2)

Supporting Data Available

None (3)


Extreme Temperatures/Humidity (1)

Shelf Life

>5 years (2)

Consumables Required

None (1)
>$1,000/year (1)
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Innova 1512

Innova 1512

LumaSense Technologies, Inc.

The LumaSense photoacoustic gas monitor INNOVA 1512 is based on the photoacoustic infrared spectrosc...

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Innova Multigas Monitors

Innova Multigas Monitors

LumaSense Technologies, Inc.

The Innova 1314 and 1512 are a quantitative gas monitors based on photoacoustic infrared detection. ...

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Sono Photonic Sensors (SPS)

Sono Photonic Sensors (SPS)

Applied Nanotech, Inc.

Sono Photonic Sensors (SPS) are used to identify trace amounts of most gases and vapors. SPS is base...

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