, Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, United States.
Anal Chem. 2022 Sep 13;94(36):12374-12382. doi: 10.1021/acs.analchem.2c01920. Epub 2022 Aug 30.
A time-domain version of photothermal microscopy using an atomic force microscope (AFM) is reported, which we call Fourier transform photothermal (FTPT) spectroscopy, where the delay between two laser pulses is varied and the Fourier transform is computed. An acousto-optic modulator-based pulse shaper sets the delay and phases of the pulses shot-to-shot at 100 kHz, enabling background subtraction and data collection in the rotating frame. The pulse shaper is also used to flatten the pulse spectrum, thereby eliminating the need for normalization by the laser spectrum. We demonstrate the method on 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pn) microcrystals and Mn-phthalocyanine islands, confirming subdiffraction spatial resolution, and providing new spectroscopic insights likely linked to structural defects in the crystals.
我们报道了一种基于原子力显微镜的光热显微镜的时域版本，我们称之为傅里叶变换光热（FTPT）光谱学，其中两个激光脉冲之间的延迟时间发生变化，并且进行傅里叶变换。基于声光调制器的脉冲整形器以 100 kHz 的频率设置脉冲的延迟时间和相位，实现了背景扣除和旋转框架下的数据采集。脉冲整形器还用于使脉冲光谱平滑化，从而无需通过激光光谱进行归一化。我们在 6,13-双（三异丙基硅基乙炔基）戊二烯（TIPS-Pn）微晶体和锰酞菁岛进行了该方法的演示，证实了亚衍射空间分辨率，并提供了可能与晶体结构缺陷相关的新光谱见解。
