Description of the OPTICAL CONSTANTS AND LAB SPECTRA OF WATER ICE bundle V1.0 ======================================================= Bundle Generation Date: 2020-02-28 Peer Review: 2010 Asteroid Review, Mon Jun 07 00:00:00 MST 2010 Discipline node: Small Bodies Node Content description based on the data set catalog file description for the PDS3 version, EAR-X-I1083-5-ICESPEC-V1.1 =================================================================================================================== Note: for PDS3 data sets migrated to PDS4, the following text is taken verbatim from the data set description and confidence level note of the PDS3 data set catalog file. In these cases, some details may not be correct as a description of the PDS4 bundle. 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 Modification History ==================== In October 2012, it was discovered that due to an error, this data set had used the same instrument ID (I0065) for its laboratory spectrometer that had been previously used for a different instrument. This caused a collision of the instrument IDs in the PDS catalog. To correct this problem, the data set, originally with data set ID EAR-X-I0065-5-ICESPEC-V1.0, was re-archived with the data set ID EAR-X-I1083-5-ICESPEC-V1.1, and with the instrument ID changed to I1083. 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. Known issues or problems with the data ====================================== 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. PDS3 Source =========== Version 1.0 of this bundle was migrated from version 1.1 of the PDS3 data set EAR-X-I1083-5-ICESPEC-V1.1.