Study of elementary photophysical and photochemical processes in organic molecules using the optoacoustical effect

Bonch-Bruevich, A. M.; Razumova, T. K.; Starobogatov, I. O.

doi:10.1007/bf00662484

Cited by 7 publications

(9 citation statements)

References 10 publications

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“…of the sample, and K a proportionality constant, including the thermoelastic properties of the solvent and the geometrical parameters (Bonch-Bruevich et al, 1977;Braslavsky et al, 1983;Jabben et al, 1984). Factor a is the fraction of the absorbed laser energy dissipated as prompt heat.…”

Section: Resultsmentioning

confidence: 99%

Study of 124-kilodalton oat phytochrome photoconversions in vitro with laser-induced optoacoustic spectroscopy

Heihoff¹,

Braslavsky²,

Schaffner³

1987

Biochemistry

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Section: Resultsmentioning

confidence: 99%

Study of 124-kilodalton oat phytochrome photoconversions in vitro with laser-induced optoacoustic spectroscopy

Heihoff¹,

Braslavsky²,

Schaffner³

1987

Biochemistry

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“…, larger nanocluster size – lower threshold level) that was used in PT-based nanodiagnosis and nanotherapy [22] . PA spectroscopy and imaging was also explored using other nonlinear phenomena such as the dependence of PA signal amplitude on temperature-dependent target or medium parameters [23–26] , photochemical reaction [27] , multiphoton absorption [28] , and absorption saturation [29] . Nevertheless, the detailed analysis of nonlinear detection of single NPs and cells in absorption background is lacking.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear photoacoustic signal amplification from single targets in absorption background

et al. 2014

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Photoacoustic (PA) detection of single absorbing targets such as nanoparticles or cells can be limited by absorption background. We show here that this problem can be overcome by using the nonlinear photoacoustics based on the differences in PA signal dependences on the laser energy from targets and background. Among different nonlinear phenomena, we focused on laser generation of nanobubbles as more efficient PA signal amplifiers from strongly absorbing, highly localized targets in the presence of spatially homogenous absorption background generating linear signals only. This approach was demonstrated by using nonlinear PA flow cytometry platform for label-free detection of circulating melanoma cells in blood background in vitro and in vivo. Nonlinearly amplified PA signals from overheated melanin nanoclusters in melanoma cells became detectable above still linear blood background. Nonlinear nanobubble-based photoacoustics provide new opportunities to significantly (5-20-fold) increase PA contrast of single nanoparticles, cells, viruses and bacteria in complex biological environments.

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“…As intensity increases, mechanisms such as saturation of the optical absorption or multiphoton/multistep absorption can occur, resulting in a nonlinear dependence of the photoacoustic signal on the excitation pulse fluence. 14,15 Saturation of the optical absorption in pulsed photoacoustic spectroscopy was previously observed in gases 16,17 and solutions. 18 However, it has never been used to extract picosecond relaxation times.…”

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confidence: 99%

Picosecond absorption relaxation measured with nanosecond laser photoacoustics

Danielli

Favazza

Maslov

et al. 2010

Applied Physics Letters

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Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast ͑femtosecond or picosecond͒ pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials. © 2010 American Institute of Physics. ͓doi:10.1063/1.3500820͔Picosecond absorption relaxation is central to many optical phenomena in physics, chemistry, biology, and medicine-such as absorption saturation, 1-3 photosynthesis, 4 and photolysis. [5][6][7] Typically, relaxation times are studied via an ultrafast ͑femtosecond or picosecond͒ pump-probe technique by measuring either fluorescence in a reflection configuration or absorption in a transmission configuration. 8,9 In the reflection-based approach, the molecules are excited by a laser pulse through the transition ͉0͘ → ͉i͘. A probe pulse with a variable delay time relative to the pump pulse monitors the time evolution of the population density N i ͑t͒. 8 When applied to molecules with low fluorescence quantum yield, this approach is noisy. In the transmission-based approach, the relaxation time is extracted by measuring pump-induced changes in probe-beam transmittivity ⌬T = T͑I p ͒ − T͑0͒, where T͑I p ͒ and T͑0͒ are the probe beam transmittivities with and without a pump of intensity I p . 9 In both approaches, the time resolution is limited by the pulse width of both the pump and the probe pulses. Hence, not only is an expensive picosecond or femtosecond laser required, but also the detection is susceptible to pulse broadening in dispersive media. Alternatively, intensity correlation of nanosecond laser pulses can be used. 10,11 Working in transmission mode, this technique is not suitable for optically thick media. All of the current techniques are limited to optically thin and weakly scattering materials or require artificial sample preparation.Photoacoustic microscopy and photoacoustic computed tomography, usually based on nanosecond laser excitation, are effective functional and molecular imaging tools in vivo. In the photoacoustic phenomenon, light is absorbed by a material and converted to heat. The subsequent thermoelastic expansion generates a detectable acoustic wave. 12 Photoacoustic sensing presents an exquisite sensitivity due to its inherent background-free nature. Its relative sensitivity to absorption reaches the theoretical limit of 100%, by far the highest among all optical imaging modalities. Most quantitative photoacoustic studies have assumed a linear dependence between ...

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Study of elementary photophysical and photochemical processes in organic molecules using the optoacoustical effect

Cited by 7 publications

References 10 publications

Study of 124-kilodalton oat phytochrome photoconversions in vitro with laser-induced optoacoustic spectroscopy

Study of 124-kilodalton oat phytochrome photoconversions in vitro with laser-induced optoacoustic spectroscopy

Nonlinear photoacoustic signal amplification from single targets in absorption background

Picosecond absorption relaxation measured with nanosecond laser photoacoustics

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