Department of Physics and Engineering and Optical Science Center for Applied Research, Delaware State University, 1200 North Dupont Highway, Dover, DE 19901 USA.
Appl Spectrosc. 2014;68(6):680-5. doi: 10.1366/13-07385.
We developed a pump-probe photothermal lens spectrophotometer that uses a broadband arc-lamp and a set of interference filters to provide tunable, nearly monochromatic radiation between 370 and 730 nm as the pump light source. This light is focused onto an absorbing sample, generating a photothermal lens of millimeter dimensions. A highly collimated monochromatic probe light from a low-power He-Ne laser interrogates the generated lens, yielding a photothermal signal proportional to the absorption of light. We measure the absorption spectra of scattering dye solutions using the device. We show that the spectra are not affected by the presence of scattering, confirming that the method only measures the absorption of light that results in generation of heat. By comparing the photothermal spectra with the usual absorption spectra determined using commercial transmission spectrophotometers, we estimate the quantum yield of scattering of the sample. We discuss applications of the device for spectroscopic characterization of samples such as blood and gold nanoparticles that exhibit a complex behavior upon interaction with light.
我们开发了一种泵浦探针光热透镜分光光度计，该仪器使用宽带弧光灯和一组干涉滤光片提供可调谐的、近单色辐射，波长范围在 370nm 至 730nm 之间，作为泵浦光源。该光聚焦在吸收样品上，产生毫米级的光热透镜。来自低功率氦氖激光器的高度准直单色探针光询问产生的透镜，产生与光吸收成正比的光热信号。我们使用该设备测量散射染料溶液的吸收光谱。我们表明，光谱不受散射的影响，这证实了该方法仅测量导致产生热的光的吸收。通过将光热光谱与使用商业透射分光光度计确定的常规吸收光谱进行比较，我们估计了样品的散射量子产率。我们讨论了该设备在光谱学特性分析中的应用，例如血液和金纳米粒子等样本，这些样本在与光相互作用时表现出复杂的行为。
