THz generation from liquid nitrogen [67
]. (a) Diagram of the apparatus for guiding an LN2
line. By filling it with LN2
, the liquid in the flask prevents the liquid in the syringe transferring heat. (b) A photo of a flowing LN2
line in an ambient environment. The transparency of the line indicates the liquid phase clearly with a smooth surface. (c) Comparison of THz waveforms from water and LN2
under the same optical excitation. Inset: corresponding spectra.