High-sensitivity infrared vibrational nanospectroscopy in water

• 来源期刊: 光：科学与应用（英文版）
• 关键词: spatial resolution vibrational spectroscopy chemical composition biological samples water absorption
• 年，卷（期）: 2017,（3）
• 页码范围: 11-15
• 页数: 5页
• 语种: 英文
• DOI: 10.1038/Isa.2017.96

摘要

Mid-infrared vibrational spectroscopy is a universal label-free tool for identifying molecular compounds in chemical and biological samples on the basis of their ‘fingerprint’ vibrational absorption lines.Vibrational spectroscopy with nanometer spatial resolution can reveal the chemical composition of samples at the nanoscale,and several scanning-probe techniques have been developed to address this need1-22.It is also highly desirable to study biological and chemical samples in their native aqueous environments rather than in air.In aqueous environments,however,the sensitivity of the current vibrational nanospectroscopy techniques deteriorates dramatically7,23.Here,we report the first mid-infrared nanospectroscopy technique that retains nanoscale sensitivity and spatial resolution when the sample and the scanning probe are completely immersed in water.This method overcomes challenges including water absorption and scattering and the mechanical damping of cantilever vibrations.We further demonstrate spectroscopy and imaging of 20-to 50-nmthick polymer samples with a 25-nm spatial resolution in the biologically relevant Amide Ⅰ and Ⅱ spectral regions.