Nitrocellulose membrane sample holder using for terahertz time domain spectroscopy

Abstract

Terahertz (THz) technology has promising applications for the detection and identification of materials because it has a great advantage in measuring material fingerprint spectrum. Terahertz time-domain spectroscopy (THz-TDS) is a key technique that is applied to spectroscopic measurement of materials. However, it is difficult to press a pellet with small mass of sample and a bulking medium such as polyethylene (PE) powder usually need to be added. Characteristic absorption peaks of the solution in liquid cell is hard to be observed due to the interaction between materials and water molecules. Therefore, one method using the hydrophilic nitrocellulose (NC) membrane as a sample holder was applied to detect samples in an aqueous medium by THz-TDS. In this study, the α-lactose samples were mixed with 20 μl of deionized water and then applied directly onto the double-layered NC membrane sample holder. This mixture is located on the gap of two piece of NC membranes. Firstly the NC membranes with different pore sizes were tested in the experiment. And then the α-lactose solutions with different concentrations were measured on the NC with different pore sizes. Consequently, the small mass of samples can be detected and the characteristic absorption peaks become stronger with the increase of NC pore size. Moreover, compared to the traditional pellet-making and liquid cell detection, this membrane method is more convenient and easy to operate.