Department of Chemistry,and the Enrico Fermi Institute
THE UNIVERSITY OF
CHICAGOChicago, IL 60637, USA
An Interactive Loomis-Wood Package For
Spectral Assignment In Igor Pro, Version 2.0
Christopher F. Neese
What is a Loomis-Wood Plot?
• A fitting function, νfit(m), is chosen to model a series in the spectrum. ν fit(m) = ν 0 + (2B”eff + ΔBeff ) m + ΔBeff m2 + … m = -J” (P-branch) or J”+1 (R-branch)
• Each line in the spectrum is assigned a value of m based on the closest predicted line.
• The residuals, ν obs - ν fit(m), of the fit are plotted versus m.
• The Loomis-Wood plot would just be a residual plot, except that every observed line is plotted, whether it is in the series or not.
Na2 (1,0) band
• F. W. Loomis and R. W. Wood, Phys. Rev. 32, 223-236 (1928).
• Fit based on Q branch.
• P and R branches clearly visible as smooth curves.
History
• Difficult to use in initial assignment process before the advent of computer.
• 1960s: First computer program to generate Loomis-Wood plots. J. F. Scott and K. N. Rao J. Mol. Spectrosc. 20, 461-
463 (1966)
• 1980s: Interactive Loomis-Wood assignment programs. B. P. Winnewisser, J. Reinstädtler, K. M. T. Yamada ,
and J. Behrend, J. Mol. Spectrosc. 136, 12-16 (1989).
Version 2.0
• The add-in is Macintosh and Windows compatible. (Version 1.0 was not Macintosh compatible.)
• There is a detailed manual and a tutorial to help users get started.• The add-in provides an organized line/assignment database.• Lines can be assigned to multiple series.• The add-in gracefully handles band heads. • Multiple Loomis-Wood data sets can be created within a single Igor
experiment.• Multiple plots of a single Loomis-Wood data set can be created
within a single Igor experiment.• There is a user-extensible extract assignments feature. This feature
allows the add-in to be used easily with external fitting programs.• Since the add-in is written for Igor (instead of as a stand-alone
program) all of Igor’s features are available to the add-in. For example, printing and graphics export are provided by Igor, not the add-in.
HCNH+ Loomis-Wood
More details TA02
HCNH+ Loomis-Wood
HCNH+ Loomis-Wood
HCNH+ Loomis-Wood
C2H4 Loomis-Wood
N2+ Loomis-Wood
Acknowledgements
• Oka Group Current Members:
• Oka• Jennifer Gottfried• Chris Morong• Aaron Schoeffler
Former Members:• Dan Hullah• Mike Lindsay• Ben McCall• Chris Tarsitano
• Norman Craig
http://fermi.uchicago.edu/freeware/
