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					                                        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 TiO2
SANDRA BRÜNKEN
Harvard-Smithsonian Center for Astrophysics, Cambridge

     63rd International Symposium on Molecular Spectroscopy, Ohio   June 19, 2008
 Astrophysical Interest
• Ti abundant transition metal; Ti/H ≈ 3 × 10−8

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

• TiO2 important ingredient of O-rich grains


 Quantum Chemical Interest
• small molecules with transition metals of fundamental interest

• transition metal compounds important as catalysts

• TiO2 common substrate for surface science
                                                      Isotopes of Titanium
Titanium monoxide TiO
                                                      46Ti:    8.25 %
                                                      47Ti:    7.44 % (I = 5/2)
                                                      48Ti:   73.72 %
                                                      49Ti:    5.41 % (I = 7/2)
  3D Electronic Ground State                          50Ti:    5.18 %



• 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)




  63rd International Symposium on Molecular Spectroscopy, Ohio           June 19, 2008
                                                     Isotopes of Titanium
Titanium monoxide TiO
                                                     46Ti:    8.25 %
                                                     47Ti:    7.44 % (I = 5/2)
                                                     48Ti:   73.72 %
                                                     49Ti:    5.41 % (I = 7/2)
 3D Electronic Ground State                          50Ti:    5.18 %




New Measurements
   • 46TiO, 50TiO First pure rotational transitions

   • Extended measurements on 48TiO

   • Data for the 3D1 3D2 states




 63rd International Symposium on Molecular Spectroscopy, Ohio           June 19, 2008
Cologne Supersonic Jet Spectrometer for Terahertz Applications (SuJeSTA)


                                                                                     He
     PLL                                            BWO-supply




                                                                    pump
                                                                           Nd:YaG
                                                                            laser
                                       BWO
                                       250 – 350 GHz


 Rb-reference




  synthesizer


                          harmonic
           PC               mixer
                                                                                 pulse
                                                                               generator
 digital lock-In                                                                 valve
                                             l-He

     63rd International Symposium on Molecular Spectroscopy, Ohio          June 19, 2008
                Laser Ablation Source for TiO and TiO2

             Pulsed Nozzle
                                        for TiO
                                        + 1 % O2

rotating                                for TiO2
 Ti rod                                 + 2-3 %                     TiO2            Nd:YaG
                                        O2                                          1064 nm


                         Pulsed Laser


     backing pressure             2 – 2,5 bar                                Multipass
    chamber pressure               5·10 5 bar
           buffer gas                   He
                                                                            10 passes
  laser energy per pulse           35 - 40 mJ
                                                                            • path length 30 cm
    width of laser pulse              6 ns
       repetition rate               30 Hz



     63rd International Symposium on Molecular Spectroscopy, Ohio          June 19, 2008
                     Spectra of           48TiO    and 46TiO in natural abundance

                                                      J : 10 ← 9
                                                      48TiO 73,8 %
                                                      46TiO  8,0 %
Intensity [a.u.]




                                                              Intensity [a.u.]




                               Frequency [GHz]                                    Frequency [GHz]



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

  Data analysis using SPFIT/SPCAT including data from Namiki et al. (1998)
         ˆ ˆ 1       ˆ ˆ ˆ            ˆ      ˆ      ˆ    2    ˆ2 ˆ        1      ˆ2 ˆ ˆ              ˆ ˆ2 ˆ2 ˆ2 ˆ2
H eff  ALZ SZ  A  LZ SZ , N 2   BN 2  DN 4  HN 6   (3SZ  S 2 )  D (3SZ  S 2 ), N 2   o( S J   S J  )
                2 D                                   3                3                     


                                        Molecular parameters for ground state TiO
                                                                This work                                                 Namiki et al. (1998)
                                46                                48                                 50                                 48
    Parameter            TiO                                    TiO                               TiO                                TiO
    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)
             7
    H x 10               -1.64 (41)                        -1.64 (41)                         -1.64 (41)                         -1.53 (60)
                      1518483.66
                                    a
                                                          1518483.66
                                                                      a
                                                                                             1518483.66
                                                                                                         a
                                                                                                                                1518477.2
    D                - 0.81782 (122)                   - 0.79413 (54)                     - 0.77486 (132)                    - 0.79422 (70)
                  52381.8
                            b
                                                      52381.8
                                                              b
                                                                                         52381.8
                                                                                                 b
                                                                                                                            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)




          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)



             63rd International Symposium on Molecular Spectroscopy, Ohio                                                 June 19, 2008
    Titanium dioxide (1A1)                          Energy Level Diagram of TiO2


                               TiO2



      dipole moment: 6.7D


• Asymmetry:  = - 0.84

• Spin statistics: Ka + Kc even allowed

• Spectrum: b-type



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

     63rd International Symposium on Molecular Spectroscopy, Ohio              June 19, 2008
                                             TiO2 rotational spectrum at 10 K

                                                  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   46TiO , 48TiO , 50TiO
                                                                                                          2       2       2
Intensity / 10-8 nm2 MHz




                                                                  Frequency [GHz]

                            63rd International Symposium on Molecular Spectroscopy, Ohio                    June 19, 2008
Energy Level Diagram of TiO2

                                                                  1588
                                        175 13            16711
                                                 176 12
                                                                  1488
                                                          1579
                                        175 13   166 10
                                                                  1386
                                                          1479
                                        165 11   156 10           1284

                                                          1377    1184
                              164 12             1468
                                        155 11
                                                          1275    1082
                              154 12             1368
                                        1459                       982
                                                          1175
                     153 13                      1266              880
                               144 10   1359              1073
                     143 11                      1166     973
                              134 10    1257
                                                 1064      871
                     133 11             1157
                              1248                964      771

                     1239     1148      1055      862
                                         955      762
                     1139     1046
                                         853      660
                     1037       946
                                         753
                      937      844       651
 10010                          744      551
                      835
                               642
                      735
                               542
  808                 633      440

  606
                      331
  404
  202          220
  000    111
Energy Level Diagram of TiO2

                                                                  1588
                                        175 13            16711
                                                 176 12
                                                                  1488
                                                          1579
                                        175 13   166 10
                                                                  1386
                                                          1479
                                        165 11   156 10           1284

                                                          1377    1184
                              164 12             1468
                                        155 11
                                                          1275    1082
                              154 12             1368
                                        1459                       982
                                                          1175
                     153 13                      1266              880
                               144 10   1359              1073
                     143 11                      1166     973
                              134 10    1257
                                                 1064      871
                     133 11             1157
                              1248                964      771

                     1239     1148      1055      862
                                         955      762
                     1139     1046
                                         853      660
                     1037       946
                                         753
                      937      844       651
 10010                          744      551
                      835
                               642
                      735
                               542
  808                 633      440

  606
                      331
  404
  202          220
  000    111
         Example of the 48TiO2 measured spectra




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




63rd International Symposium on Molecular Spectroscopy, Ohio             June 19, 2008
          Stable isotopomers of titanium dioxide

                                 46TiO     - 8,0 %
                                      2
                                 47TiO    - 7,3 %
                                      2
                                 48TiO    - 73,8 %
                                      2
                                 49TiO    - 5,5 %
                                      2
                                 50TiO    - 5,4 %
                                      2


                                 JKa,Kc : 75,3 ← 64,2




63rd International Symposium on Molecular Spectroscopy, Ohio   June 19, 2008
                                                    Analysis of TiO2

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


                                Ground state molecular constants for TiO2
                                                           This work                                           Brünken et al.
                               46                            48                            50                             48
     Parameter                TiO2                          TiO2                          TiO2                           TiO2
     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)
     DJ x 10 
            3
                         -8.379 51 (129)              8.348 07 (129)                 -8.319 21 (128)                8.363 2 (123)
     DJK x 10  3
                       -96.735 9 (267)              -94.617 6 (261)                 -92.680 2 (255)               -94.397 (110)
     DK 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 10 
            6
                         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
                                 Conclusion

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

				
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