Terahertz Absorption Terahertz Absorption Terahertz Absorption - PowerPoint PPT Presentation

Terahertz Absorption Terahertz Absorption Terahertz Absorption Terahertz Absorption Spectrum of Liquid Water Spectrum of Liquid Water Spectrum of Liquid Water Spectrum of Liquid Water Indara Suarez Pasadena City College INSET Physics Mentor: Jing Xu Faculty Advisor: Prof. S. James Allen Funded by: NASA & Army Research Office (ARO) 8/1/2003 1

Motivation Motivation Motivation Motivation � To Study the Physical Property of Liquid Water. � Terahertz Absorption Spectrum of Water: • Not Well Established • Few Powerful Terahertz Sources • Only Recent Development in Terahertz Optics Approach Approach Approach Approach � Direct Absorption Measurement: • How Much Does the Media Absorb per Thickness? • P nout ∝ exp (-t n α ) 8/1/2003 2

Experimental Experimental Experimental Experimental Apparatus Apparatus Apparatus Apparatus F THz E t P out ∝ e -t α L t = Sample Thickness 0.08 μm Sample holder 0.16 µm 0.20 µm 0.24 µm 8/1/2003 3

Preliminary Data Preliminary Data Preliminary Data Preliminary Data 0.8 P out (V) 0.6 signal 0.4 0.2 0.0 0 200 400 600 800 1000 Time (µsec ) Absorption 20 15 n ∝ e -tn α P out P out (V) 10 5 0 0 1 2 3 4 5 8/1/2003 4 Thickness ( μm)

Absorption Coefficient Absorption Coefficient Absorption Coefficient Absorption Coefficient Ln(P outn ) ∝ - t n α 6 4 n ) 2 Ln(P out 0 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 -2 Thickness( μm) -4 -6 y = -35.09x + 4.4237 -8 -10 α = 35.09 μm -1 , R 2 = 94.8% 8/1/2003 5

Future Work Future Work Future Work Future Work • Create A Spectrum of the Absorption Coefficients of Liquid Water in the Terahertz Range. • Compare Data with Current Theories of Absorption Spectrum of Liquid Water. • Measure Terahertz Absorption Spectrum of Liquid Water with Biomaterial. 8/1/2003 6

Acknowledgements Acknowledgements Acknowledgements Acknowledgements Professor Jim Allen Jing Xu Professor Kevin Plaxco Mike Wrocklage Liu-Yen Kramer Trevor Hirst Al Flinck Nick Arnold Mike Northen Mel McLaurin Eric Hoffmann National Science Foundation Army Research Office NASA 8/1/2003 7

Terahertz Circular Terahertz Circular Dichroism Dichroism Dichroism Terahertz Circular Terahertz Circular Dichroism Spectroscopy Spectroscopy Spectroscopy Spectroscopy • Argument: – Well structured, chiral, stereochemically-pure macromolecules are a universal sign of life. • Approach: – Making a spectrometer that will detect & fingerprint these macromolecules. • Hopeful Conclusion: – Finding life. (funded by NASA) – Finger-printing and identifying biological polymers. (funded by the ARO) 8/1/2003 8

Circular Dichroism: Differential Measurement Phase Difference Result Circularly Polarized 0° Light 200 µ m 180° 90° -90° Rutgers-Newark Department of Chemistry Eric Hoffmann 8/1/2003 9