%0 Journal Article %J Chemical Physics Letters %D 2000 %T Pulsed terahertz spectroscopy of DNA, bovine serum albumin and collagen between 0.1 and 2.0 THz %A Markelz, A. G. %A Roitberg, A. %A Heilweil, E. J. %K b-dna %K Chemistry %K films %K modes %K Physics %K proteins %X

We report the first use of pulsed terahertz spectroscopy to examine low-frequency collective vibrational modes of biomolecules. Broadband absorption increasing with frequency was observed for lyophilized powder samples of calf thymus DNA, bovine serum albumin and collagen in the 0.06-2.00 THz (2-67 cm(-1)) frequency range, suggesting that a large number of the low-frequency collective modes for these systems are IR active. Transmission measurements at room temperature showed increasing FIR absorption with hydration and denaturing. (C) 2000 published by Elsevier Science B.V. All rights reserved.

%B Chemical Physics Letters %V 320 %P 42-48 %8 Mar %@ 0009-2614 %G English %9 Article %M WOS:000086211200008 %R 10.1016/S0009-2614(00)00227-X %0 Journal Article %J Applied Physics Letters %D 1998 %T Temperature-dependent terahertz output from semi-insulating GaAs photoconductive switches %A Markelz, A. G. %A Heilweil, E. J. %K domain %K generation %K Physics %K pulses %K semiconductor surfaces %K transmission spectroscopy %X

The temperature dependence of the terahertz (THz) output power and spectra from biased photoconductive switches was measured for several antenna gap widths and applied biases. The spectrally integrated THz output had a nonmonotonic temperature dependence in all cases with the value increasing by a factor of 3 from room temperature to 150 K for low biases and 100 K at high biases. An abrupt decrease in output power occurs below 90 K, and the spectrum shifts to lower frequencies as the temperature is lowered. (C) 1998 American Institute of Physics.

%B Applied Physics Letters %V 72 %P 2229-2231 %8 May %@ 0003-6951 %G English %9 Article %M WOS:000073362300011 %! Appl. Phys. Lett.Appl. Phys. Lett. %R 10.1063/1.121329