White Light Photothermal Lens Spectrophotometer for the Determination of Absorption in Scattering Samples
White Light Photothermal Lens Spectrophotometer for the Determination of Absorption in Scattering Samples
复制标题
用于测定散射样品吸收的白光光热透镜分光光度计
作者：
A. Marcano;Salvador Alvarado;Junwei Meng;Daniel Caballero;E. M. Moares;R. Edziah
我们研制了一台泵浦探测光热透镜分光光度计，它使用宽带弧光灯和一组干涉滤光片来提供可调的、在370到730 nm之间的近单色辐射作为泵浦光源。这种光聚焦在吸收样品上，产生毫米尺寸的光热透镜。来自低功率He-Ne激光器的高度准直的单色探测光询问产生的透镜，产生与光的吸收成正比的光热信号。利用该装置测量了散射染料溶液的吸收光谱。我们证明了光谱不受散射的存在的影响，证实了该方法只测量导致热产生的光的吸收。通过将光热光谱与商用透射式光谱仪测得的常见吸收光谱进行比较，我们估算了样品的散射量子产率。我们讨论了该设备在血液和金纳米颗粒等样品的光谱表征中的应用，这些样品在与光相互作用时表现出复杂的行为。
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.