Data Set Overview
  =================
    The data set consists of 54 infrared spectra of amorphous and crystalline
    H2O-ice collected in the laboratory. The vacuum system used has been
    described previously (Hudgins et al., 1993; Bernstein et al., 2006). To
    summarize, we collect infrared transmission spectra of ice samples
    deposited on a window suspended under high vacuum (~10-8 mbar) and at low
    cryogenic temperatures (~15 K).
 
    The basic protocol for our experiments is as follows. We first cool the
    sample window to the desired temperature and record a background spectrum
    of 1000 scans. We vapor deposit the sample while monitoring the IR
    spectrum and sample thickness (see below). In our experiments, the maximum
    temperature of the sample determines the phase of H2O ice. We observe that
    crystalline samples that were created by depositing at low temperature and
    heating to the point of crystallization produces a spectrum that is
    different from crystalline samples made by directly depositing gas at
    temperatures above 140 K.  The largest change is seen in the position of
    the band near 6050 cm-1 (1.65 microns), which shifts from 6037 cm-1 (1.656
    microns) when deposited at 100 K to 6027 cm-1 (1.659 microns) when
    deposited at 150 K.   Therefore, all crystalline samples are deposited on
    a 150 K sample window, while amorphous samples are deposited on the sample
    window at temperatures of 100 K and lower.
 
    The optical constants, the real and imaginary part of the index of
    refraction (n,k), were calculated using a Kramers-Kronig relation
    (Mastrapa, et al. 2008).
 
    The naming convention for the files is: phase_temperature.txt.  For
    example, crystalline h2o-ice at 20 K is crys_20K.txt.  The files that
    begin with 'min' are the minimum values for the corresponding spectrum.
    That is, the minimum value spectra for 20 K crystalline h2o-ice is
    min_crys_20K.txt.  Instead of numbers, the amorphous h2o-ice files are
    either high or low temperature.
 
    Also included with the data are the original spectra used for the
    calculation in the folder: original_spectra. These files consist of two
    columns of tab-delimted text.  The first column is frequency in wave
    numbers (1/cm) and the second column is % transmission. These spectra have
    not been baseline corrected or had the infrared interference fringes
    removed.  For each set of optical constants, several spectra were
    averaged, resulting in a single spectrum. The spectra used for a given
    temperature and phase are listed below.
 
    Amorphous High Temperature
    21sept06_4.txt
    17april06_3.txt
    17april06_4.txt
    12april06_9.txt
    12april06_10.txt
 
    Amorphous Low Temperature
    19sept06_2.txt
    19sept06_3.txt
    19sept06_4.txt
    19sept06_5.txt
    19sept06_6.txt
 
    Crystalline 20 K
    8sept06_14.txt
    13sept06_14.txt
    15sept06_2.txt
 
    Crystalline 30 K
    8sept06_15.txt
    8sept06_13.txt
    13sept06_13.txt
    13sept06_15.txt
    15sept06_3.txt
 
    Crystalline 40 K
    8sept06_16.txt
    8sept06_12.txt
    13sept06_12.txt
    13sept06_16.txt
    15sept06_4.txt
 
    Crystalline 50 K
    8sept06_17.txt
    8sept06_11.txt
    13sept06_11.txt
    15sept06_5.txt
 
    Crystalline 60 K
    8sept06_10.txt
    13sept06_10.txt
    15sept06_6.txt
 
    Crystalline 70 K
    8sept06_9.txt
    13sept06_9.txt
    15sept06_7.txt
 
    Crystalline 80 K
    8sept06_8.txt
    13sept06_8.txt
    15sept06_8.txt
 
    Crystalline 90 K
    8sept06_7.txt
    13sept06_7.txt
    15sept06_9.txt
 
    Crystalline 100 K
    8sept06_6.txt
    13sept06_6.txt
    15sept06_10.txt
 
    Crystalline 110 K
    8sept06_5.txt
    13sept06_5.txt
    15sept06_11.txt
 
    Crystalline 120 K
    8sept06_4.txt
    13sept06_4.txt
 
    Crystalline 130 K
    8sept06_3.txt
    13sept06_3.txt
 
    Crystalline 140 K
    8sept06_2.txt
    13sept06_2.txt
 
    Crystalline 150 K
    15sept06_1.txt
    8sept06_1.txt
    13sept06_1.txt
 
    Reference
    =========
 
    Mastrapa, R.M., M.P. Bernstein, S.A. Sandford, T.L. Roush, D.P.
    Cruikshank, D. P., and C. M. Dalle Ore, Optical constants of amorphous and
    crystalline H2O-ice in the near infrared from 1.1 to 2.6 microns, Icarus
    197, 307-320, 2008.

Confidence Level Overview
  =========================
    In general, the signal to noise ratio for the spectra is very high. The
    largest contribution of error is the surface scattering properties of the
    ice samples.  This leads to variation in continuum levels and slope. There
    are values that are near 100% transparency of the material which lead to
    unrealistically low values of k.