A database of molecular spectra accurate to high
temperatures and pressures
PI: Scott T. Sanders, Assistant Professor, UW-Madison,
Engine Research Center, Department of Mechanical Engineering,
12 September 2006
This whitepaper presents an aggressive program designed to
revolutionize the understanding and implementation of gas molecular spectra,
particularly at high temperatures and/or high pressures.
Members of the Engine Research Center plan to team with
other experts (e.g., spectroscopic modelers) in this effort. Contact Prof.
Sanders if you are interested in joining the effort.
- Measure gas absorption and emission spectra over a
controlled range of temperatures and pressures in the Engine Research Center using recently developed test facilities.
- Spectra will be highly resolved (< 0.1 cm-1
resolution), and span a very broad range of wavelengths (200 – 20,000
- Temperatures to 3000 K
- Pressures to 100 bar
- Species targeted:
- Any species of interest, provided
room-temperature absorption features stronger than 1%/meter can be
realized somewhere in the 200 – 20,000 nm range
- The most popular candidates: OH, H2O, CO2
- Other popular candidates: NO, CH2O,
O2, hydrocarbons, CO
- Countless species can be measured, but larger test
matrices cost more to measure. See budget section below.
- The measurements are based on a new twist to traditional
Fourier-transform spectroscopy concepts.
- Based on measured spectra, upgrade existing spectral
models so that accurate spectra can be generated anywhere in the T = [300
.. 3000K], P = [1 .. 100 bar] range.
- Create a web-based tool that allows visitors to plot /
download absorption and/or emission spectra (as well as corresponding spectra
from databases such as HITRAN / HITEMP if desired)
- In addition to spectra, fundamental information such as
spectroscopic data and detailed spectral model functions will also be
available from the web tool.
The below plots compare measured
and simulated ν1+ν3 H2O vapor
- Discrepancies in line positions and line strengths at high
- Discrepancies in spectral broadening at high pressures and
temperatures (note that the measured features are spectrally narrow
compared to the simulated features):
Why is this database important?
- Spectral databases such as HITRAN, HITEMP, CDSD, LIFBASE,
LIFSIM, and others (including, for example, other atmospheric databases)
will be improved and/or supplanted. At elevated temperatures and
pressures, only a handful of gas spectra are treated in the above databases,
and even in these cases, reliability is uncertain. As the countless
optical sensors based on such databases continue to evolve and become dedicated
to applications, the fidelity of the databases becomes increasingly
important. More complete and more accurate databases are needed in many
- Improving the performance of existing optical diagnostics
- Identifying new opportunities for optical diagnostics and
sensors: e.g., detecting species with poorly-understood spectra or
species in the presence of stronger interfering absorbers
Such applications span many fields
including chemistry, astronomy, biology, physics, and engineering.
- Improving the understanding of molecular structure and
other properties that are derived from fundamental spectroscopic data (thermodynamic
properties, chemical properties, etc.)
- Ultimately such data and its application will lead to
tangible progress including improved performance of energy-conversion and
industrial processes, improved military systems, etc.
Approximate minimum budget:
Equipment (1000-20,000 nm range)
Additional equipment (200-1000 nm)
Experimental facility setup
Cost per species per octave in temperature; full pressure
range, mostly personnel time
Cost per species; full temperature and pressure range,
mostly personnel time
$140k + $33k/species IR
$190k + $33k/species UV-IR
For more information contact Prof. Sanders,