Ramer Georg, Reisenbauer Florian, Steindl Benedikt, Tomischko Wolfgang, Lendl Bernhard
1 Institute for Chemical Technologies and Analytics, Technical University of Vienna, Vienna, Austria.
2 Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Appl Spectrosc. 2017 Aug;71(8):2013-2020. doi: 10.1177/0003702817695290. Epub 2017 Mar 14.
Photothermal-induced resonance (PTIR) is a method for optical spectroscopy that allows for infrared (IR) chemical imaging at spatial resolution below the limit of diffraction. By using the mechanical resonance of the cantilever for amplification the technique has been shown to allow sensitivity down to single monolayers. In this work, we discuss the challenges that must be overcome for performing stable resonant PTIR measurements and how imprecise experimental procedures can lead to irreproducible or even erroneous results. We also present a controller design that continuously readjusts the excitation frequency of a PTIR setup back to the resonance frequency in order to allow for accurate resonance-enhanced PTIR measurements. This controller can be used together with a broad range of atomic force microscopes. Schematics and program code for the controller are made freely available.
光热诱导共振（PTIR）是一种光谱学方法，可实现空间分辨率低于衍射极限的红外（IR）化学成像。通过利用悬臂的机械共振进行放大，该技术已被证明灵敏度可达单层。在这项工作中，我们讨论了进行稳定的共振PTIR测量必须克服的挑战，以及不精确的实验程序如何导致不可重复甚至错误的结果。我们还提出了一种控制器设计，该设计可将PTIR装置的激发频率持续重新调整回共振频率，以实现精确的共振增强PTIR测量。该控制器可与多种原子力显微镜一起使用。控制器的原理图和程序代码可免费获取。
