Related Experiment Video
Updated: Jun 15, 2026

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces
Published on: July 26, 2016
Photoacoustic determination of small optical absorption coefficients: extended theory
Abstract:
Photoacoustic measurement of small absorption coefficients provides an important alternative to standard techniques. The theoretical basis for such measurements is extended to include the effects of thermally generated mechanical motion of the sample, by incorporating the thermoelastic equations for an isotropicm solid in a cylindrical configuration. Sample calculations show that this thermoacoustic effect may dominate the photoacoustic signal for certain modulation frequencies and beam configurations.
Related Concept Videos
UV–Vis Spectroscopy: Beer–Lambert Law
Atomic Absorption Spectroscopy: Interference
Spectral interference occurs when signals from other elements or molecules overlap with the analyte signal, falsely elevating or masking the analyte's absorbance. This interference can be corrected using Zeeman,...
Inductively Coupled Plasma Atomic Emission Spectroscopy: Instrumentation
There are three main types of inductively coupled plasma atomic emission spectroscopy (ICP-AES) instruments: sequential, simultaneous multichannel, and Fourier transform instruments, with the latter being less commonly used.
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to the...

