Recent measurements of electrostrictiona body force term commonly excluded from calculations of electromagnetic force and momentum density-cast new light on a long-standing debate in the history of electrodynamic theory.

In this work, we review the main existing theories for the electromagnetic stress–energy tensor in dielectric media — a problem directly related to the century-long debate regarding the correct momentum of light in dielectric media, known as Abraham–Minkowski controversy. The theoretical validity of the main existing formulations is analyzed in terms of symmetry and invariance requirements for the tensors. We also present position- and time-dependent numerical simulations of the related electromagnetic forces for a lossless nondispersive medium, highlighting the different expected spatial force distributions. The force densities of different formulations drive forward different momentum and atomic number density distributions of the medium contributing to the total momentum and energy densities associated with the coupled field-medium state of light.

Precise control over light-matter interactions is critical for many optical manipulation and material characterization methodologies, further playing a paramount role in a host of nanotechnology applications. Nonetheless, the fundamental aspects of interactions between electromagnetic fields and matter have yet to be established unequivocally in terms of an electromagnetic momentum density. Here, we use tightly focused pulsed laser beams to detect bulk and boundary optical forces in a dielectric fluid. From the optical convoluted signal, we decouple thermal and nonlinear optical effects from the radiation forces using a theoretical interpretation based on the Microscopic Ampère force density. It is shown, for the first time, that the time-dependent pressure distribution within the fluid chiefly originates from the electrostriction effects. Our results shed light on the contribution of optical forces to the surface displacements observed at the dielectric air-water interfaces, thus shedding light on the long-standing controversy surrounding the basic definition of electromagnetic momentum density in matter.

We demonstrate the influence of edge effects on the photothermal-induced phase shift measured by a homodyne quadrature laser interferometer and compare the experiments with rigorous theoretical descriptions of thermoelastic surface displacement of metals. The finite geometry of the samples is crucial in determining how the temperature is distributed across the material and how this affects the interferometer phase shift measurements. The optical path change due to the surface thermoelastic deformation and thermal lens in the surrounding air is decoded from the interferometric signal using analytical and numerical tools. The boundary/edge effects are found to be relevant to properly describe the interferometric signals. The tools developed in this study provide a framework for the study of finite size effects in heat transport in opaque materials and are applicable to describe not only the phase shift sensed by the interferometer but also to contribute to the photothermal-based technologies employing similar detection mechanisms.

Laser-induced wavefront distortion is detectable by several techniques based on the photothermal effect. The effect is probed by monitoring the phase shift caused by the bulging of the heated area, the photoelastic effects, and the spatial distribution of the refractive index within the sample and in the fluid surrounding it. A simple analytical solution for the wavefront distortion was only possible for low absorbing materials, with the assumption that the stresses obey either the thin-disk or the long-rod type distributions. Recently, a unified theoretical description for the laser-induced optical path change was proposed to overcome part of this limitation for weakly absorbing materials, regardless of its thickness. In this work, we perform an experimental investigation taking the sample–fluid heat coupling effect into account using the thermal lens technique. The experimental investigation presented here validates the unified model. In addition, we show that the heat-coupling model provides an alternative method to obtain physical properties of non-absorbing fluid by using a reference solid sample.

A portable photoacoustic device is designed and applied to measure thermal diffusivity and linear thermal expansion coefficient of glassy carbon by means of the standard photoacoustic model involving both the thermal diffusion and thermoelastic contributions. This is done by measuring the evolution of the open-cell photoacoustic signal within the modulation frequency interval of 20 Hz-10 kHz, for four samples with thicknesses of 180μm, 140μm, 100μm, and 60μm. A proper fitting procedure of the theoretical amplitude and phase to their corresponding experimental counterparts yielded an average thermal diffusivity of 0.68mm^2·s^-1 and expansion coefficient of \(4.3\times 10^{-6}\) K-1 which are in good agreement with their values reported in the literature for glassy carbon. Furthermore, we demonstrate that the theoretical amplitude does not properly describe the thermoelastic behavior of the samples thinner than \(l \le 100\) μm, due to their strong bending and vibrations driven by the highly disordered fullerene microstructure of glassy carbon followed by the increasing non-homogeneity effects violating 1D heat conduction.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

We investigate the thermoelastic waves launched by a localized heat deposition. Pulsed laser excitation is used to generate mechanical perturbations in metals that are detected using the photothermal mirror method. This method detects the wavefront distortion of the probe beam reflected from the perturbed sample surface. Nanometer scale expansion of the material is induced just under the irradiated surface releasing transient thermoelastic waves of much smaller amplitudes on the surface. Numerical predictions and the experimental results are in a good agreement and represent both the thermal diffusion of the large amplitude, long-lasting outward bulge, and the released elastic waves.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

The second edition of the Glossary of Terms Used in Photochemistry [Pure Appl. Chem.68, 2223–2286 (1996); ] has been both corrected and updated. Terms have been added related to molecular anisotropy, the use of polarized radiation, nonlinear optical phenomena, and the emerging field of computation of excited species. Some changes have been introduced in this “Glossary” regarding the terms related to radiation energy to make this collection fully compatible with internationally agreed-upon terms. Many links are included to various Web pages listing quantities relevant to the work of photochemists and scientists using photochemical tools.

Recent improvements in the modeling of photo-induced thermo–optical–mechanical effects have broadened the application of photothermal techniques to a large class of solids and fluids. During laser excitation, changes in optical reflectivity due to temperature variation may affect the photothermal signal. In this study, the influence of the reflectivity change due to heating is analyzed for two pump–probe photothermal techniques, thermal lens and thermal mirror. A linear equation for the temperature dependence of the reflectivity is derived, and the solution is tested using optical properties of semi-transparent and opaque materials. For semi-transparent materials, the influence of the reflectivity change in photothermal signals is less than 0.01%, while for opaque materials it is lower than 3%.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.

This paper presents quantities, terminology, and symbols of terms related to photothermal phenomena and used in photothermal and related spectroscopies. The terms used in the literature to describe photothermal phenomena and methods are reviewed, and a glossary of terms is given. The origins of photothermal phenomena, as well as the relations among various photothermal effects, are summarized. The listed terms cover the terminology in transient grating, transient lens, photoacoustic spectroscopy, photothermal radiometry, calorimetry, interferometry, deflection, reflection, and other related spectroscopies, which use or are related to photothermal effects.