Search results
Results from the WOW.Com Content Network
Photoacoustic spectroscopy is the measurement of the effect of absorbed electromagnetic energy (particularly of light) on matter by means of acoustic detection. The discovery of the photoacoustic effect dates to 1880 when Alexander Graham Bell showed that thin discs emitted sound when exposed to a beam of sunlight that was rapidly interrupted with a rotating slotted disk.
Photoacoustic imaging or optoacoustic imaging is a biomedical imaging modality based on the photoacoustic effect.Non-ionizing laser pulses are delivered into biological tissues and part of the energy will be absorbed and converted into heat, leading to transient thermoelastic expansion and thus wideband (i.e. MHz) ultrasonic emission.
Photoacoustic spectroscopy is also useful for the opposite case of opaque samples, where the absorption is essentially complete. In an arrangement where a sensor is placed in a gaseous phase above the sample and the light impinges the sample from above, the photoacoustic signal results from an absorption zone close to the surface.
Mie theory has been used in the detection of oil concentration in polluted water. [30] [31] Mie scattering is the primary method of sizing single sonoluminescing bubbles of air in water [32] [33] [34] and is valid for cavities in materials, as well as particles in materials, as long as the surrounding material is essentially non-absorbing.
Tunable diode laser absorption spectroscopy (TDLAS, sometimes referred to as TDLS, TLS or TLAS [1]) is a technique for measuring the concentration of certain species such as methane, water vapor and many more, in a gaseous mixture using tunable diode lasers and laser absorption spectrometry.
Most fluorochromes are optimized for fluorescence emission and are sub-optimal for optoacoustic detection, because after absorbing the illuminating energy, they tend to emit fluorescence rather than convert it to heat and generate a photoecho. Dyes with higher absorption cross-sections generate stronger optoacoustic signals.
The argon gas is ionized in the intense electromagnetic field and flows in a particular rotationally symmetrical pattern towards the magnetic field of the RF coil. A stable, high temperature plasma of about 7000 K is then generated as the result of the inelastic collisions created between the neutral argon atoms and the charged particles. [5]
Optoacoustic imaging could refer to: Photoacoustic imaging; Multispectral optoacoustic tomography This page was last edited on 11 November 2016, at 16:44 (UTC) ...