Transcript I2-2005.ppt

A molecular iodine atlas in ascii format
Houssam Salami and Amanda Ross
Laboratoire de Spectrométrie Ionique et Moléculaire,
Université Lyon I & CNRS (UMR 5579) Villeurbanne, France.
An invitation to use a Doppler-limited absorption spectrum, available on the Web …
Why record (yet another) spectrum of the B-X transitions of I2?
Not for the B-X spectroscopy of iodine! Only to calibrate excitation spectra.
The information already exists :
1) Aimé Cotton Atlas of Gerstenkorn and co-workers (in four parts).

In paper format

Corrections are required at short wavelengths.
2) Sub-Doppler Atlas (Katô and co-workers) « Hors Concours »
3) From tabulated parameters. (calculated spectrum, e.g.commercial Iodine Spec)
Our motivation : an excitation spectrum of NiH.
NiH fluorescence,
~17400 cm-1.
Nice spectrum.
Inadequate wavemeter / temperature stabilized F-P fringes.
Recording the absorption spectrum of I2
Transmission spectrum recorded in 4 pieces (with appropriate optical filters).
Instrumental resolution 0.02 cm-1.
50 cm iodine cell, heated according to wavelength region of interest.
Wavenumber range
Filters
Temperature
(°C)
19100 - 20500
Corning CS 4-97 + Corning CS 5-56
20
16500 - 19500
Corning CS 4-97
20
15400 - 17400
Corning CS 3-67 + Corion LS 650
50
14500 – 16500
Corning CS 2-61 + Corion LS 700
190
I2 B-X absorption spectrum
Reference
HeNe laser
Close Up … Doppler limited iodine lines still have odd shapes!
How does the calibration compare with other sources ?
Circles : LASIM – Aimé Cotton atlas
Triangles : LASIM – Katô atlas
Applied to an excitation spectrum of NiH
Q (3 ½)
Comparison reveals non-linear scan of
the laser, but calibration is quite
feasible.
Q (2 ½)
Conclusion
The spectrum was recorded to solve a local problem, but could
probably prove useful elsewhere.
It is freely available …
We’re working on software to calibrate from this atlas automatically.
Has been submitted to Journal of Molecular Spectroscopy.