The Pure Rotational Spectrum of PbI from
Broadband Rotational Spectroscopy
Daniel P. Zaleski, Hansjochen Köckert, Susanna L.
Stephens, Nick R. Walker
School of Chemistry, Bedson Building, Newcastle University, Newcastle upon
Tyne, NE1 7RU, UK.
Lisa-Maria Dickens and Corey Evans
Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK.
The Ohio State 69th International Symposium on Molecular Spectroscopy, June 19th, 2014.
Introduction
PbI has a 2П1/2 ground state
Radical diatomics in this state have garnered interest in the past
- SnCl
- PbCl (RC07 2010 ISMS)
J. Mol. Spectrosc., 2012, 280, 85-90.
J. Mol. Spectrosc., 1998, 191, 108-116.
There has been spectroscopic in the past for PbI.
Chem. Phys. Lett., 1992, 190, 271-278.
J. Mol. Spectrosc., 1993, 161, 552-559.
Chirped Pulse FTMW Spectroscopy
Broadband spectrometers with instantaneous
frequency coverage from 2-8 GHz, 6.5-18.5 GHz,
18.5-26 GHz, and 25 – 40 GHz have been
constructed.
Current Technology:
AWG
Digital Oscilloscope
24 Gs/s (12 GHz)
100 Gs/s (33 GHz)
No Coils
Dynamic Range
~10,000:1
600k FID’s
CF3I, 6 bar Ar, Pb rod
3 Primary Isotopes:
208Pb
200x
~52%
207Pb ~22%
206Pb ~24%
S/N ~50:1
Exp.
Theory*
B (MHz)
818.2834(3)
790.2489
D (kHz)
0.092(2)
A (THz)
|239.034|
a (MHz)
186.85(5)
d (MHz)
239.76(1)
eQq (MHz)
-701.42(5)
𝟏
𝟐
− (p+2q) (MHz)
𝟏
𝟐
− (q) (MHz)
207Pb
spin 1/2
163.142(4)
-21.0(3)
* MP2/aug-cc-pVTZ-PP
Chem. Phys. Lett., 1992, 190, 271-278.
𝐵𝑒 =
1
(15𝐵0 − 10𝐵1 + 3𝐵2 )
8
Be = 819.3010(7) MHz
𝛼𝑒 = 2𝐵0 − 3𝐵1 + 𝐵2
αe = 2.0352(9) MHz
~241 kJ/mol
ωe = 161.02(4) cm-1
𝜔𝑒 𝑥𝑒 = 𝐵𝑒
𝛼𝑒 𝜔𝑒
+1
6𝐵𝑒2
2
ωeχe = 9690(12) MHz
𝜔𝑒2
𝐷𝐸 =
4𝜔𝑒 𝑥𝑒
DE = 20003(2178) cm-1
𝑈 𝑟 = 𝐷𝐸 1 − 𝑒 −𝑎(𝑟−𝑟𝑒 ) ²
Chem. Phys. Lett., 1992, 190, 271-278.
3 Primary Isotopes:
300x
120Sn
~32%
118Sn ~24%
116Sn ~14%
S/N ~30:1
Exp.
Theory*
B (MHz)
1120.2711(4)
1126.6139
D (kHz)
0.1608(5)
A (THz)
|72.19|
a (MHz)
224.71(7)
d (MHz)
99.96(3)
eQq (MHz)
-697.6(2)
𝟏
𝟐
− (p+2q) (MHz)
-143.285(2)
* MP2/aug-cc-pVTZ-PP
MC-SCF
Be = 1121.7667(9) MHz
αe = 2.991(9) MHz
γe = 0.9(5) kHz
~311 kJ/mol
ωe = 241.1(1) cm-1
ωeχe = 16740(16) MHz
DE = 25971(2823) cm-1
𝑈 𝑟 = 𝐷𝐸 1 − 𝑒 −𝑎(𝑟−𝑟𝑒 ) ²
Trans. Farad. Soc.,1967, 64, 616-619.
Conclusions
Both PbI and SnI have a 2П1/2 ground state
Assigned a number of vibrational states for each of the Pb and Sn isotopes
Modeled the PES using Morse potential
ED are on the order of ~240 – 310 kJ/mol
Acknowledgments
University of Bristol
Colin Western
Engineering and Physical
Sciences Research Council
AWE
(Aldermaston)