1. 8
16.00 90
232.0 92
238.0 17
35.45 68
167.3 53
126.9
& 62
150.4
10.81 5
32.1 16 57
138.9
DETECTION AND CHARACTERIZATION OF THE STANNYLENE (SnH2) FREE RADICAL IN THE GAS PHASE
TONY C. SMITH, Ideal Vacuum Products, LLC, Albuquerque, NM DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY

2. TIN: 7 MAJOR AND 3 MINOR (<1%) ISOTOPES
In fact, Tin has the most stable isotopes of all elements!
Xenon is next with 8 stable isotopes, followed by Cadmium and Tellurium, with 6 each.
The spectra of Tin containing molecules can be complicated by isotope splittings.

3. SnH2 and SnD2 are unknown in the gas phase!
EXPERIMENTAL BACKGROUND
1. Infrared Spectra of the Novel Sn2H2 Species and the Reactive SnH1,2,3 and PbH1,2,3 Intermediates in Solid Neon, Deuterium, and Argon, Xuefeng Wang, Lester Andrews, George Chertihin, P. F. Souter, J. Phys. Chem. A 106, 6302 (2002).
(Laser ablation studies of tin and lead and their reactions with hydrogen studied by IR matrix spectroscopy)
SnH2 and SnD2 are unknown in the gas phase!

4. MO PICTURE ↑↓ b1 n(Sn 5px) n(lone pair) b2 (Sn-H) (bonding) a1
90o <H-Sn-H o ↑↓ a1 b2 b1

5. Geometries: B3LYP/aug-cc-pVTZ-pp
AB INITIO POTENTIALS
Geometries: B3LYP/aug-cc-pVTZ-pp
Barrier To Linearity
~ 8000 cm-1

6. SnH2 SYNTHESIS FOR JET SPECTROSCOPY
Sn(CH3)4 or SnH4 + Argon

7. TETRAMETHYL TIN YIELDS NEW SPECTRA IN THE DCM REGION

8. LIF SPECTRA FROM SnH4 & SnD4 in the DCM REGION

9. SnD2 LIF SPECTRA 20 2
Sn2
Sn2
Sn2 3 20

10. 0-0 BAND LIF SPECTRUM OF SnH2
All transitions to lowest Ka= 0
levels in the excited state.

11. Transitions to Ka = 1 much weaker than expected
SnD BAND LIF SPECTRUM ANALYSIS
Transitions to Ka = 1 much weaker than expected

12. RESOLUTION OF THE TIN ISOTOPES

13. Long bending progressions as expected for a large change in bond angle
EMISSION SPECTRA
Long bending progressions as expected for a large change in bond angle

14. FLUORESCENCE LIFETIMES
240 ns
20,2
Rotational Energy
670 ns
10,1
1350 ns
00,0
Fluorescence lifetimes decrease rapidly
with increasing rotational energy

15. HOLE BURNING TO PROBE DARK ROVIBRONIC STATES
Dark State
Bright State
Fluorescence Intensity
l Probe Laser
Ground State
Probe
Pump

16. HOLE BURNING SPECTRA
Pump Laser
Probe Laser
LIF

17. rR1(1) HOLE BURNING SPECTRA & 220 LIFETIMES
V2=0
V2=1
V2=2
6 ps
4 ps
2 ps
𝟎 𝟎 𝟎 𝑩𝒂𝒏𝒅
𝟐 𝟎 𝟏 𝑩𝒂𝒏𝒅
𝟐 𝟎 𝟐 𝑩𝒂𝒏𝒅
220 fluorescence lifetimes decrease rapidly with increasing vibrational energy

18. MOLECULAR STRUCTURES B 1B1 X 1A1 ~ 1.738(5) Å 123.0(3) ~ 1.774(3) Å
91.0(2)

19. PREDISSOCIATION MECHANISM

20. CONCLUSIONS SnH2 and SnD2 have been observed in the gas phase.
SnH4 readily dissociates in an electric discharge to produce SnH2.
LIF spectra show that SnH2 is rotationally predissociated in the excited state.
Rotational analysis and hole burning expts. were used to derive rotational constants.
The r0 molecular structure of the stannylene radical has been determined for both states.