1. By Madhu Gyawali Narayan Adhikari Yadab Paudel FTIR Measurements on November 06,08 at Reno Nov 18, 08 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV

2. Introduction, Instrumentation: Nov 18, 08 FTIR is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, 5 microns to 20 microns. FTIR collects infrared spectra by an interferogram of a sample signal using an interferometer, then performs a Fourier Transform on the interferogram to obtain the spectrum. An interferometer is an instrument that uses the technique of superimposing (interfering) two or more waves, to detect differences between them. The FTIR spectrometer uses a Michelson interferometer. (Source-Pat Arnott,ATMS 749) PHYS 749 UNIVERSITY OF NEVADA, RENO,NV http://en.wikipedia.org/wiki/Fourier_transform

3. Introduction… Nov 18, 08 PHYS 749 Figures: From Lecturer’s Note (Pat Arnott) IR Window 8-13 microns. IR radiation from the Earth’s surface escapes to space (cooling the Earth). Absorption by O 3 near 9 microns ‘dirties’ the window. UNIVERSITY OF NEVADA, RENO,NV

4.  Cloudy sky: window region high temperature (≈ 275 K, 7:28AM )  Clear sky: Lower temperature from deep surface ( ≈ 180K, 12 :00AM )  Surface temperature ≈ 278-285K Results: Temperature Vs. Wave number Nov 18, 08 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV

5. Results: Temperature Vs. Wave number Nov 18, 08  Co2 peaks around wave number 670 cm-1 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV

6. Results: Temperature Vs. Wave number Nov 18, 08 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV

7. Results: Radiance Vs. wave number Nov 18, 08 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV

8. Results: Irradiance Vs. wave number (model) Nov 18, 08 PHYS 749 UNIVERSITY OF NEVADA, RENO,NV