NIR Optical constants spectrum of CH4 (normalized to 100%) in solid solution in alpha-N2 crystal at 35 K
- Title
- NIR Optical constants spectrum of CH4 (normalized to 100%) in solid solution in alpha-N2 crystal at 35 K
- DOI
- 10.26302/SSHADE/EXPERIMENT_BS_20130103_003
- Data reference
- Quirico, Eric; Schmitt, Bernard (1992): NIR optical constant spectra of CH4 in solid solution in alpha and beta-N2 phases at 5 different temperatures (35K - 43K). SSHADE/GhoSST (OSUG Data Center). Dataset/Spectral Data. https://doi.org/10.26302/SSHADE/EXPERIMENT_BS_20130103_003
- Publications
- Database
- Experimentalists
- Experiment type
- laboratory measurement
- Type
- optical constants
- Comments
- This spectrum is only valid for CH4:alpha-N2 solid solutions with CH4 concentrations lower than 2% - The fundamental N2 band (2235-2520cm-1) is not removed - The top of the nu3 fundamental CH4 band (2985-3090cm-1) is missing (saturated) - Data can be used for reflectance spectra simulation in the 2985-3090cm-1 range except for very low CH4 concentrations or small N2 grain sizes (i.e. when CH4 nu3 band not saturated)
- Instrument
- Nicolet 800 – transmission Near-IR
- Sample holder
- Stainless steel closed cell 10 mm thick with MgF2 windows cooled by He cryostat in UHV chamber with 2 KBr windows
- Standard medium
- vacuum
- Observation mode
- spectrum
- Spectral range type(s)
- NIR
- Valid spectral range(s)
-
Min - Max ($cm^{-1}$) Sampling ($cm^{-1}$) Resolution ($cm^{-1}$) Position accuracy ($cm^{-1}$) Absorption edge #1 2520.0 - 2985.0 #2 3090.0 - 10000.0 - Comments
- Noisy (mostly k < 5e-6) in the 3620-3830, 4760-5530, 6200-7050, 7410-7480, 7550-8550, and 8930-10000 cm-1
- Comments
- C axis possibly perpendicular to beam axis
Illumination
- Type of polarization
- no
Observation
- Type of polarization
- no
- Comments
- possibly partly polarized beam by beamsplitter
- Observation mode
- single spot
- Image size
- 2.5 x 2.5 $mm$
- Resolutions
- 2.5 ${\pm}$ 0.5 $mm$
- Comments
- circular spot located in center of a monocrystal
- Experiment
- NIR optical constant spectra of CH4 in solid solution in alpha and beta-N2 phases at 5 different temperatures (35K - 43K)
- Date begin
- 1998-03-17
- Release date
- 2018-02-27 11:44:05 UTC+0000
- Version (Date)
- #1 (2018-02-27 11:44:05 UTC+0000)
- History
-
Date Mode Version Status Comments 2018-02-07 10:26:31 UTC+0000 first import #1 valid version new optical constants spectrum of CH4 in solid solution in alpha-N2 at 35K (near-IR)
- Analysis
- The absorption coefficient of diluted CH4, normalized to a concentration of 1, is calculated by substracting the absorbance spectrum of pure alpha-N2 (2nu range only) from the absorbance spectrum of CH4 diluted in alpha-N2 (from Quirico and Schmitt 1997a). The imaginary part 'k' is then derived in the limit of small k values (k < 1e-2), i.e., with k = alpha/(4*pi*nu). The real part 'n' values is constant and equal to the visible value of N2 (n = 1.23). See Quirico et al. 1999
- Quality flag
- 4
- Validator(s)