Hyperspectral Raman imaging using Bragg tunable filters of graphene and other low-dimensional materials

Hyperspectral Raman imaging is presented as a powerfulmethod to acquire quantitative aswell as qualitative information on low-dimensional materials. The method is, however, not widely used due to limitations of the Raman scanning instruments. Here we present a hyperspectral Raman system based on Bragg tunable filtering that is capable of global imaging with significantly reduced acquisition time and improved sensitivity compared to scanning confocal Raman microscopes. The operation principles of the instrument are presented, and the performance is benchmarked using a calibrated carbon nanotube sample. Examples of various applications are shown to illustrate the abilities of the technique to characterize samples deposited on oxidized silicon substrates, including graphene stacks prepared by chemical-vapor deposition, exfoliated MoS₂, and carbon nanotubes filled with dye molecules. The wealth of information available through this hyperspectral Raman imaging technique opens many new ways to probe the properties of complex low-dimensional materials.