698 research outputs found
Small carbon chains in circumstellar envelopes
Observations were made for a number of carbon-rich circumstellar envelopes
using the Phoenix spectrograph on the Gemini South telescope to determine the
abundance of small carbon chain molecules. Vibration-rotation lines of the
antisymmetric stretch of C near 2040 cm (4.902 m)
have been used to determine the column density for four carbon-rich
circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We
additionally calculate the column density of C for IRC +10216, and
provide an upper limit for 5 more objects. An upper limit estimate for the
C column density is also provided for IRC+10216. A comparison of these
column densities suggest a revision to current circumstellar chemical models
may be needed
Empirical line lists and absorption cross sections for methane at high temperature
Hot methane is found in many "cool" sub-stellar astronomical sources
including brown dwarfs and exoplanets, as well as in combustion environments on
Earth. We report on the first high-resolution laboratory absorption spectra of
hot methane at temperatures up to 1200 K. Our observations are compared to the
latest theoretical spectral predictions and recent brown dwarf spectra. The
expectation that millions of weak absorption lines combine to form a continuum,
not seen at room temperature, is confirmed. Our high-resolution transmittance
spectra account for both the emission and absorption of methane at elevated
temperatures. From these spectra, we obtain an empirical line list and
continuum that is able to account for the absorption of methane in high
temperature environments at both high and low resolution. Great advances have
recently been made in the theoretical prediction of hot methane, and our
experimental measurements highlight the progress made and the problems that
still remain.Comment: 9 pages, 5 figures and 3 tables. For associated online data see
http://dx.doi.org/10.1088/0004-637X/813/1/1
Experimental energy levels of the water molecule
Experimentally derived energy levels are presented for 12 248 vibration–rotation states of the H2 16O isotopomer of water, more than doubling the number in previous, disparate, compilations. For each level an error and reference to source data is given. The levels have been checked using energy levels derived from sophisticated variational calculations. These levels span 107 vibrational states including members of all polyads up to and including 8v. Band origins, in some cases estimates, are presented for 101 vibrational modes
Effectiveness of In-School Suspension as Used in Selected Washington State Public Schools
Current in-school suspension programs and their effectiveness were studied. Selected junior high schools and middle schools in the state of Washington were surveyed, and twenty-one responded with information concerning their in-school suspension programs. The results showed that in-school suspension programs in Washington state, if established with certain fundamental criteria, are an effective alternative to out of school suspension. They also provide a learning process for discipline cases at the junior high school and middle school levels
Emission spectrum of hot HDO in the 380-2190 cm(-1) region
Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 degreesC. The spectra were recorded in three overlapping sections and cover the wavenumber range 380-2190 cm(-1). A total of 22106 lines were measured, of which 60% are thought to belong to HDO. A total of 6430 FIDO transition,, are assigned, including the first transitions to the (040) vibrational state, with a term value of 5420.042 cm(-1). A total of 1536 new energy levels of HDO belonging to the (000), (010) (020), (030), and (040) stated are presented, significantly extending the degree of rotational excitation compared to previous studies. (C) 2001 Elsevier Science
ACE-FTS Observations of Acetonitrile in the Lower Stratosphere
This work reports the first infrared satellite remote-sensing measurements of acetonitrile (CH3CN) in the Earth\u27s atmosphere using solar occultation measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) between 2004 and 2011. The retrieval scheme uses new quantitative laboratory spectroscopic measurements of acetonitrile (Harrison and Bernath, 2012). Although individual ACE-FTS profile measurements are dominated by measurement noise, median profiles in 10 degrees latitude bins show a steady decline in volume mixing ratio from similar to 150 ppt (parts per trillion) at 11.5 km to \u3c 40 ppt at 25.5-29.5 km. These new measurements agree well with the scant available air-and balloon-borne data in the lower stratosphere. An acetonitrile stratospheric lifetime of 73 ± 20 yr has been determined
Hot methane line lists for exoplanet and brown dwarf atmospheres
We present comprehensive experimental line lists of methane (CH4) at high
temperatures obtained by recording Fourier transform infrared emission spectra.
Calibrated line lists are presented for the temperatures 300 - 1400 degC at
twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns)
region of the infrared. This range encompasses the dyad, pentad and octad
regions, i.e., all fundamental vibrational modes along with a number of
combination, overtone and hot bands. Using our CH4 spectra, we have estimated
empirical lower state energies (Elow in cm-1) and our values have been
incorporated into the line lists along with line positions (cm-1) and
calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line
lists to find direct application in the modeling of planetary atmospheres and
brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal
referenc
Emission spectrum of hot HDO below 4000 cm-1
Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 °C. The spectra were recorded in three overlapping sections and cover the wavenumber range 1800–3932 cm−1. This spectrum is analyzed together with a previously reported one spanning the 380–2190 cm−1 range [Parekunnel et al., J. Mol. Spectrosc. 2001 (28) 101]. This analysis leads to 4409 newly assigned HDO emission lines. This work particularly extends data on the (200) and (120) states of HDO for which newly determined energy levels are presented
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