supersonic jet spectroscopy on tio 2 millimeter-wave spectroscopy of titanium monoxide and titanium...

Supersonic Jet Spectroscopy on TiO2

Millimeter-wave Spectroscopy of

Titanium Monoxide and Titanium Dioxide

63rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

PATRIK KANIA, THOMAS F. GIESEN, HOLGER S. P. MÜLLER, STEPHAN SCHLEMMERI. Physikalisches Institut, Universität zu Köln

SANDRA BRÜNKENHarvard-Smithsonian Center for Astrophysics, Cambridge

• TiO abundant in M & S stars; absorption used for classification

• TiO2 important ingredient of O-rich grains

• transition metal compounds important as catalysts

• TiO2 common substrate for surface science

• Ti abundant transition metal; Ti/H ≈ 3 × 10−8

Astrophysical Interest

• small molecules with transition metals of fundamental interest

Quantum Chemical Interest


• Optical : A – X band system study,

R. S. Ram, P. F. Bernath, M. Dulick, and L.Wallace, ApJS, 122, 331 (1999)

• Infrared: No rotationally resolved data available

• Millimeter wave: 220 – 460 GHz 48TiO main isotope K. Namiki, S. Saito, J.S. Robinson, and T.C. Steimle, J. Mol. Spectrosc. 191, 176-182 (1998)

Titanium monoxide TiO

3 Electronic Ground State

Isotopes of Titanium 46Ti: 8.25 %47Ti: 7.44 % (I = 5/2)48Ti: 73.72 %49Ti: 5.41 % (I = 7/2)50Ti: 5.18 %

New Measurements

• 46TiO, 50TiO First pure rotational transitions

• Extended measurements on 48TiO

• Data for the 31 32 states

Titanium monoxide TiO

3 Electronic Ground State

Isotopes of Titanium 46Ti: 8.25 %47Ti: 7.44 % (I = 5/2)48Ti: 73.72 %49Ti: 5.41 % (I = 7/2)50Ti: 5.18 %


PLL

beam splitter

Rb-reference

BWO-supply

BWO

harmonic mixer

He

pulse generator

valve

l-He

digital lock-In

PC

synthesizer

pu

mp

250 – 350 GHz

Nd:YaGlaser


Cologne Supersonic Jet Spectrometer for Terahertz Applications (SuJeSTA)

Pulsed Laser

Laser Ablation Source for TiO and TiO2

backing pressure 2 – 2,5 bar

chamber pressure 5·10 5 bar

buffer gas He

laser energy per pulse 35 - 40 mJ

width of laser pulse 6 ns

repetition rate 30 Hz

Multipass

10 passes

• path length 30 cm

Pulsed Nozzle

rotating Ti rod

for TiO+ 1 % O2

for TiO2

+ 2-3 % O2


Nd:YaG1064 nm

TiO2

J : 10 ← 9


Spectra of 48TiO and 46TiO in natural abundance

Frequency [GHz] Frequency [GHz]

Inte

nsity

[a.

u.]

Inte

nsity

[a.

u.]

48TiO 73,8 %46TiO 8,0 %

Data analysis using SPFIT/SPCAT including data from Namiki et al. (1998)

Molecular parameters for ground state TiO This work Namiki et al. (1998)

Parameter 46TiO 48TiO 50TiO 48TiO

B 16 177.070 26 (218) 16 003.552 79 (138) 15 843.788 18 (234) 16 003.408 14 (154)

D 0.0185032 (132) 0.0180560 (129) 0.0177302 (127) 0.0180606 (168)

H x 107 -1.64 (41) -1.64 (41) -1.64 (41) -1.53 (60)

1518483.66a 1518483.66a 1518483.66a 1518477.2

D - 0.81782 (122) - 0.79413 (54) - 0.77486 (132) - 0.79422 (70)

52381.8b 52381.8b 52381.8b 52380.0

D 0.0194825 (72) 0.0194825 (72) 0.0194825 (72) 0.01494 (100)

x 103 0.73 (46) 0.73 (46) 0.73 (46) 0.73 (46)

Analysis of TiO

Parameters are given in MHz. Standard deviations of all parameters given in parentheses are in units of the corresponding last digits.a, b Fixed to the value of R. S. Ram, P. F. Bernath, M. Dulick, and L.Wallace, ApJS, 122, 331 (1999)

eff 2 2 4 6 2 2 2 2 2 2 2 2 2Z Z Z Z Z

DZD ˆ

1 2 1ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ, (3 ) (3 ), ( )2 3 3

H L S L S N N N N SA A B S S S N SH o JD S J


• Asymmetry: = - 0.84

• Spin statistics: Ka + Kc even allowed

• Spectrum: b-type


TiO2

dipole moment: 6.7D

Energy Level Diagram of TiO2

S. Brünken, H. S. P. Müller, K. M. Menten, M. C. McCarthy, and P. Thaddeus, ApJ 676, 1367 (2008)

Titanium dioxide (1A1)

First pure rotational studies of TiO2

S. Brünken, H. S. P. Müller, K. M. Menten, M. C. McCarthy, and P. Thaddeus, ApJ 676, 1367 (2008)

27 observed transitions in the 7 – 42 GHz range for three isotopomers 46TiO2, 48TiO2, 50TiO2


Inte

nsity

/ 1

0-8 n

m2 M

Hz

Frequency [GHz]

TiO2 rotational spectrum at 10 K

000

202

404

606

808

10010

111

220

331

440

771

871

973

1073

1175

1275

1377

1479

1579

16711

880

982

1082

1184

1284

1386

1488

1588

660

762

862

964

1064

1166

1266

1368

1468

156 10

166 10

176 12

551

753

853

955

1055

1157

1257

1359

1459

155 11

165 11

175 13

175 13

651

744

844

946

1046

1148

1248

134 10

144 10

154 12

164 12

633

735

835

937

1037

1139

1239

133 11

143 11

153 13

642

542

Energy Level Diagram of TiO2

JKa,Kc : 85,3 ← 74,4 JKa,Kc : 95,5 ← 84,4


Example of the 48TiO2 measured spectra

46TiO2 - 8,0 %47TiO2 - 7,3 %48TiO2 - 73,8 %49TiO2 - 5,5 %50TiO2 - 5,4 %

JKa,Kc : 75,3 ← 64,2

Stable isotopomers of titanium dioxide


Data fitted to A-reduced Watson Hamiltonian including data from (Brünken et al. 2008)

Analysis of TiO2

Ground state molecular constants for TiO2 This work Brünken et al.

Parameter 46TiO2 48TiO2

50TiO2 48TiO2

A 31 051.479 43 (168) 30 520.540 96 (132) 30 031.664 58 (164) 30 520.541 48 (165)

B 8 471.564 34 (36) 8 471.758 010 (305) 8 471.935 13 (41) 8 471.758 38 (54)

C 6 638.200 87 (48) 6613.587 28 (41) 6 590.319 30 (48) 6 613.587 31 (47)

J x 103 -8.379 51 (129) 8.348 07 (129) -8.319 21 (128) 8.363 2 (123)

JK x 103 -96.735 9 (267) -94.617 6 (261) -92.680 2 (255) -94.397 (110)

K x 103 757.404 (63) 732.662 (61) 710.238 (59) 732.445 (151)

J x 103 2.964 22 (66) 2.979 97 (66) 2.994 44 (66) 2.981 5 (40)

K x 103 17.283 (49) 16.798 (48) 16.345 (47) 16.819 (141)

K x 106 64.04 (80) 60.89 (76) 58.02 (73) 39.3 (85)

KJ x 106 -7.81 (37) -7.49 (35) -7.20 (34)

K x 106 5.89 (209) 5.64 (200) 5.42 (192)

Parameters are given in MHz. Standard deviations of all parameters given in parentheses are in units of the corresponding last digits

Isotopics ratios kept fixed for distortion parameters

TiO

• First pure rotational transitions of 46TiO and 50TiO

• Isotopic invariant fit in progress

TiO2

• Extended measurements up to J = 22, Ka = 8 (T= 150 K)

• Higher order centrifugal parameters • Data for astronomical observations

Conclusion

supersonic jet spectroscopy on tio 2 millimeter-wave spectroscopy of titanium monoxide and titanium...

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