Optoacoustic spectroscopy for real-time monitoring of strongly light-absorbing solutions in applications to analytical chemistry

Abstract

An optoacoustic technique for solutions of strongly light-absorbing analytes at 0.1–0.01 mol l−1 is proposed. The technique is based on the wide-band forward mode detection of temporal profiles of laser-generated ultrasonic pulses (optoacoustic signals). The leading edge of the signal repeats the distribution of the laser fluence in the medium, which makes it possible to determine its optical absorption and investigate its dynamics during a reaction. The range of light-absorption coefficients starts from 1 to 5 and reaches 104 to 105 cm−1. The determination of iron(II) as ferroin shows the possibility of probing 0.1 mol l−1 of iron(II), which was not previously achieved for this reaction by optical spectroscopy. To further prove the concept, kinetic measurements for ferroin decomposition at the level of 0.1 mol l−1 and at high pHs are performed. The results are compared with spectrophotometry at lower concentrations and show good reproducibility and accuracy of kinetic constants.

Molecular fingerprinting of nanoparticles in complex media with non-contact photoacoustics: beyond the light scattering limit

“…The PA method was first applied (to our knowledge) to accurately measure the light absorption coefficient in homogeneously absorbing solutions in 69 , which was then extended to strongly scattering (or turbid) media 4 , 5 , 70 – 72 . Recently, the method was proposed and applied in analytic chemistry to analyze optically dense solutions 73 , 74 .…”

Absorption spectra of nanodiamond aqueous dispersions by optical absorption and optoacoustic spectroscopies

“…We propose optoacoustic ( OA ) spectroscopy along with UV/vis and differential scanning calorimetry ( DSC ) measurements for qualifying ND samples. The advantage of the approach is that OA modalities respond to absorption (at least for dilute samples) and that light-scattering media are acoustically transparent to a certain extent [ 44 , 45 ]. Thus, this method can be used for measurement of high absorbances characteristic for practically relevant ND samples.…”

Optoacoustic response of gold nanorods in soft phantoms using high-power diode laser assemblies at 870 and 905 nm

“…Optical imaging offers good spatial resolution but is limited to a few millimeters in biological tissues [7]. In this regard, optoacoustic tomography (OAT) and microscopy (OAM) have been developed as non-invasive alternatives to the existing imaging techniques, due to their ability of acquiring high-resolution images from deep tissues by using non-ionizing laser radiation [8,9]. They combine the good spatial resolution and the high penetration depth of ultrasonic imaging with the strong optical absorption contrast of optical imaging for functional cancer detection at early stages [10][11][12][13].…”