This paper presents a method for measuring the optical absorption cross-sections (σ(a)) of Au-Ag nanocages and Au nanorods. The method is based on photoacoustic (PA) imaging, where the detected signal is directly proportional to the absorption coefficient (μ(a)) of the nanostructure. For each type of nanostructure, we firstly obtained μ(a) from the PA signal by benchmarking against a linear cal...

At room temperature, CO2 is transparent in the ultraviolet (UV) at wavelengths longer than 205 nm; however, at temperatures above 1000 K the CO2 absorption cross-section becomes significant in the region between 200 and 320 nm. Because CO2 is a major product of hydrocarbon combustion and because both the magnitude of the absorption cross-section and the shape of the UV absorption spectrum vary ...

Recent measurements of transmission versus fluence for a methanol-solvated asymmetric pentaazadentate porphyrin-like (APPC) cadmium complex, @(C6H4 – APPC)Cd]Cl, showed the limitations of current energy-level models in predicting the transmission behavior of organic reverse saturable absorbers at fluences greater than 1 J/cm2. A new model has been developed that incorporates higher-order triple...

The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D) metamaterial-assisted electromagnetic superabsorber with arbitrary geometries are derived and validated by numerical simulation....

Gold nanocages of <40 nm in dimension have been synthesized using the galvanic replacement reaction between Ag nanocubes and HAuCl4 in an aqueous solution. By controlling the molar ratio between Ag and HAuCl4, the gold nanocages could be tuned to display surface plasmon resonance peaks around 800 nm, a wavelength commonly used in optical coherence tomography (OCT) imaging. OCT measurements on p...

We theoretically study the optical performance of a layered nanoparticle with a sandwiched gain shell. Based on quasi-static analysis and full-wave numerical simulations, we show that it is possible to achieve a very high scattering cross-section (over 4 orders) accompanied with a negative absorption cross-section by changing the amount of gain in the sandwiched shell layer. This suggests that ...

An ab initio theory is devised for the x-ray photoabsorption cross section of atoms in the field of a moderately intense optical laser (10 W cm2 ). The laser dresses the core-excited atomic states, which introduces a dependence of the cross section on the angle between the polarization vectors of the two linearly polarized radiation sources. We use the Hartree-Fock-Slater approximation to descr...

Small three-photon absorption (3PA) cross-section values of present nonlinear organic molecules limit their practical applications. Although electron donors and electron acceptors have a great effect on 3PA cross-section, little is known about how the strength and situation of electron acceptors influence the 3PA cross-section value of a compound. The present work reports 3PA effects of two flu...