Millimeterwave Spectroscopy of Titanium Monoxide and Titanium Dioxide

Millimeter-wave Spectroscopy of Titanium Monoxide and Titanium Dioxide PATRIK KANIA, THOMAS F. GIESEN, HOLGER S. P. MÜLLER, STEPHAN SCHLEMMER I. Physikalisches Institut, Universität zu Köln Supersonic Jet Spectroscopy on Ti. O 2 SANDRA BRÜNKEN Harvard-Smithsonian Center for Astrophysics, Cambridge 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Astrophysical Interest • Ti abundant transition metal; Ti/H ≈ 3 × 10− 8 • Ti. O abundant in M & S stars; absorption used for classification • Ti. O 2 important ingredient of O-rich grains Quantum Chemical Interest • small molecules with transition metals of fundamental interest • transition metal compounds important as catalysts • Ti. O 2 common substrate for surface science

Titanium monoxide Ti. O Isotopes of Titanium 46 Ti: 47 Ti: 48 Ti: 3 D Electronic Ground State 49 Ti: 50 Ti: 8. 25 % 7. 44 % (I = 5/2) 73. 72 % 5. 41 % (I = 7/2) 5. 18 % • Optical : A – X band system study, R. S. Ram, P. F. Bernath, M. Dulick, and L. Wallace, Ap. JS, 122, 331 (1999) • Infrared: No rotationally resolved data available • Millimeter wave: 220 – 460 GHz 48 Ti. O main isotope K. Namiki, S. Saito, J. S. Robinson, and T. C. Steimle, J. Mol. Spectrosc. 191, 176 -182 (1998) 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Titanium monoxide Ti. O Isotopes of Titanium 46 Ti: 47 Ti: 48 Ti: 3 D Electronic Ground State 49 Ti: 50 Ti: 8. 25 % 7. 44 % (I = 5/2) 73. 72 % 5. 41 % (I = 7/2) 5. 18 % New Measurements • 46 Ti. O, 50 Ti. O First pure rotational transitions • Extended measurements on 48 Ti. O • Data for the 3 D 1 3 D 2 states 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Cologne Supersonic Jet Spectrometer for Terahertz Applications (Su. Je. STA) PLL BWO-supply BWO 250 – 350 GHz Rb-reference be am sp lit pump He Nd: Ya. G laser te r synthesizer PC harmonic mixer pulse generator valve digital lock-In l-He 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Laser Ablation Source for Ti. O and Ti. O 2 Pulsed Nozzle for Ti. O + 1 % O 2 rotating Ti rod for Ti. O 2 + 2 -3 % O 2 Ti. O 2 Nd: Ya. G 1064 nm Pulsed Laser backing pressure 2 – 2, 5 bar chamber pressure 5· 10 5 bar buffer gas He laser energy per pulse 35 - 40 m. J width of laser pulse 6 ns repetition rate 30 Hz 63 rd International Symposium on Molecular Spectroscopy, Ohio Multipass 10 passes • path length 30 cm June 19, 2008

Spectra of 48 Ti. O and 46 Ti. O in natural abundance J : 10 ← 9 73, 8 % 46 Ti. O 8, 0 % Intensity [a. u. ] 48 Ti. O Frequency [GHz] 63 rd International Symposium on Molecular Spectroscopy, Ohio Frequency [GHz] June 19, 2008

Analysis of Ti. O Data analysis using SPFIT/SPCAT including data from Namiki et al. (1998) 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, Ap. JS, 122, 331 (1999) 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Titanium dioxide (1 A 1) Energy Level Diagram of Ti. O 2 dipole moment: 6. 7 D • Asymmetry: = - 0. 84 • Spin statistics: Ka + Kc even allowed • Spectrum: b-type S. Brünken, H. S. P. Müller, K. M. Menten, M. C. Mc. Carthy, and P. Thaddeus, Ap. J 676, 1367 (2008) 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Ti. O 2 rotational spectrum at 10 K First pure rotational studies of Ti. O 2 S. Brünken, H. S. P. Müller, K. M. Menten, M. C. Mc. Carthy, and P. Thaddeus, Ap. J 676, 1367 (2008) 46 Ti. O 2, 48 Ti. O 2, 50 Ti. O 2 Intensity / 10 -8 nm 2 MHz 27 observed transitions in the 7 – 42 GHz range for three isotopomers Frequency [GHz] 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Energy Level Diagram of Ti. O 2 1588 175 13 164 12 153 13 1459 1468 1368 1266 1157 1239 1148 1055 862 1139 1046 955 762 853 660 1037 946 937 844 606 000 155 11 1248 633 331 220 156 10 1257 735 111 165 11 134 10 835 404 202 166 10 1359 133 11 808 175 13 144 10 143 11 10010 176 12 744 642 542 440 753 651 551 16711 1488 1579 1386 1479 1284 1377 1184 1275 1082 1175 982 1073 1166 973 1064 871 964 771 880

Energy Level Diagram of Ti. O 2 1588 175 13 164 12 153 13 1459 1468 1368 1266 1157 1239 1148 1055 862 1139 1046 955 762 853 660 1037 946 937 844 606 000 155 11 1248 633 331 220 156 10 1257 735 111 165 11 134 10 835 404 202 166 10 1359 133 11 808 175 13 144 10 143 11 10010 176 12 744 642 542 440 753 651 551 16711 1488 1579 1386 1479 1284 1377 1184 1275 1082 1175 982 1073 1166 973 1064 871 964 771 880

Example of the 48 Ti. O 2 measured spectra JKa, Kc : 85, 3 ← 74, 4 63 rd International Symposium on Molecular Spectroscopy, Ohio JKa, Kc : 95, 5 ← 84, 4 June 19, 2008

Stable isotopomers of titanium dioxide 46 Ti. O - 8, 0 % 47 Ti. O 7, 3 % 2 48 Ti. O - 73, 8 % 2 49 Ti. O 5, 5 % 2 50 Ti. O 5, 4 % 2 2 JKa, Kc : 75, 3 ← 64, 2 63 rd International Symposium on Molecular Spectroscopy, Ohio June 19, 2008

Analysis of Ti. O 2 Data fitted to A-reduced Watson Hamiltonian including data from (Brünken et al. 2008) 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

Conclusion Ti. O • First pure rotational transitions of 46 Ti. O and 50 Ti. O • Isotopic invariant fit in progress Ti. O 2 • Extended measurements up to J = 22, Ka = 8 (T= 150 K) • Higher order centrifugal parameters • Data for astronomical observations