Near-Infrared Spectroscopy of Interstellar and Planetary Ice Analogs

Amanda M. Cook

Dr. Perry A. Gerakines

Research Funded by a grant from the NSF REU program

Where are ices detected?

• Interstellar CloudsInterstellar Clouds

• CO: Triton, Pluto, CometsCO: Triton, Pluto, Comets

• NHNH33: Miranda, Charon: Miranda, Charon

• CHCH44: Triton, Pluto, Kuiper Belt Objects, : Triton, Pluto, Kuiper Belt Objects,

CometsComets

Spectroscopy• Bending Modes

• Stretching Modes

• Resonance

O

H H

Combined Near-IR and Mid-IR Spectra of N2+CH4

10000 8000 6000 4000 2000

0.0

0.5

1.0

1.5

Abs

orba

nce

Wavenumber (cm-1)

Experimental Set-up

Turbo-pump

Helium CoolingSystem

Gas Bulb

UV lamp

Infrared Beam from Spectrometer

Sample Chamber

NH3+CO Photolysis Products

10000 8000 6000 4000 2000-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Unphotolyzed Sample

Photolyzed Sample

Ab

so

rba

nce

Wavenumber (cm-1)

A Closer Look…

7000 6500 6000 5500 5000 4500 4000-0.2

0.0

Photolyzed Sample

Unphotolyzed Sample

Abs

orba

nce

Wavenumber (cm-1)

NH3+CO Photolysis Product

4760 4740 4720 4700 4680 4660 4640-0.05

-0.04

-0.03

-0.02

48 hr UV Deposit (30K) 48 hr UV Deposit (11K) 44 hr UV Deposit (11K) 36 hr UV Deposit (11K) Unphotolyzed Deposit

Abs

orba

nce

Wavenumbers (cm -1)

Quirico and Schmitt (1997)

5400 5200 5000 4800 46000.0

0.2

Pure CO2 Deposit

Abs

orba

nce

Wavenumber (cm-1)

Pure CO2 Deposit Pure Ethylene

Identifying the Feature

Triton Spectrum

Cruikshank et al. (1993)

N2+CH4 Photolysis Products

10000 8000 6000 4000 2000

0.0

0.5

1.0

1.5

2.0

Unphotolyzed Sample

Photolyzed Sample

Absorb

ance

Wavenumber (cm-1)