1. RAIRS of Methanol on Cu(110) and Cu-O striped phase Priyanka Singnurkar

2. Outline RAIRS of Methanol on clean Cu(110)
RAIRS of Methanol on Cu(110)-(2×1)O striped phase
Summary

3. Motivation
Methanol is the smallest alcohol molecule and a technologically important molecule whose synthesis and oxidation is catalysed by ,e.g.,copper.
Though methanol is simple ,its oxidation process on catalytic surfaces exhibits a surprisingly large complexity with several different possible reaction routes.

4. Experimental set up The UHV apparatus consists of two main parts-
The experimental chamber
RAIRS

5. Expeimental Chamber
Schematic diagram of the UHV-chamber and measuring instruments of the first level

6. Schematic diagram of the second level

7. Measurment Devices XPS (X-ray photo electron spectroscopy)
QMS (Quadrupole mass spectroscopy)

8. RAIRS Attachement Bruker IFS 66v/S FTIR –Spectrometer ,
External MCT Detector ,
Grazing incidence (~83°),
Scan time ~15 min

9. IR Spectra on clean Cu(110)

10. IR intensity vs Exposure at differenet temperature
n CO

11. Wavenumber vs Exposure & Amplitude vs Exposure

12. Reaction Path on Clean Cu(110)
CH3OH(g)  CH3OH(a)  CH3O(a)  CH2O
Methanol(g)
Methanol(a)
Methoxide(a)
Formaldehyde

13. IR During Thermal Desorption
During desorption
formaldehyde
methanol
E.DEmirci,J.Stettner,M.Kratzer,R.Schennach,and A.Winkler Journal of chemical physics 126,164710(2007

14. Wavenumber Vs Temperature on clean Cu(110)

15. RAIRS ON STRIPED PHASE

16. IR spectra collected during thermal desorption
0.25ML Oxygen at 550K
Methanol exposure at 200K
Desorption with 0.1 K/s
IR with 60KHz frequency,1min scan time and resolution of 4 cm-1

17. RAIRS & TPD on striped phase
0.25ML oxy+12LCH3OH at 100K
1098
1098
formaldehyde
methanol
Temperatur(K)
E.DEmirci,J.Stettner,M.Kratzer,R.Schennach,and A.Winkler Journal of chemical physics 126,164710(2007

18. IR spectra on striped phase

19. Wavenumber Vs Temperature on striped surface
Tads = 200 K
Tads = 100 K

20. Reaction Paths on Striped Cu(110)
CH3OH(g) CH3OH(a)
CH3OH(a)+O(a) CH3O(a)+OH
2CH3O 2H2CO(a)+2H
2H(a) H2(g)
H2CO(a) H2CO(g) OR
CH2O(a)+O(a) HCOO(a)+H
2HCOO(a) 2CO2(g)+H2(g)

21. SUMMARY
During 50L exposure on clean Cu (110), along with other reaction products, a vibrational feature around wavenumber 980 cm-1 is found which could be formaldehyde.This feature was absent on the striped phase.
Desorption experiment on clean surface shows a vibrational feature at around 1090 cm-1 which could be formate.
Desorption from striped phase has same features as after 50 L methanol on clean surface.

22. ACKNOWLEDGEMENT
Robert Schennach
Adolf Winkler
Erkan Demirci

23. Thank you for your attention!