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CH2Br2 Absorption and C+ REMPI Scans Overview

This presentation provides an overview of the absorption spectrum of CH2Br2 and its correlation with C+ REMPI scans. It includes information on absorption cross sections, ionization limits, and predictions for atomic lines. The data is sourced from various papers and databases.

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CH2Br2 Absorption and C+ REMPI Scans Overview

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  1. CH2Br2: 1) Absorption 2) REMPI scans: overview (slides 12-15) 3) C+ REMPI vs absorption spectrum agust,www,....ch2br2/PPT-010311ak.ppt agust,heima,...CH2Br2/PXP-010311ak.pxpagust,heima,...CH2Br2/PXP-020311ak.pxp agust,heima,...CH2Br2/PXP-050311ak.pxp agust,heima,...CH2Br2/C REMPI-130411jl.pxp

  2. Searched for “CH2Br2 absorption” in Google:

  3. nm

  4. Details Bibliography: G.C. Causley and B.R. Russell, "Vacuum ultraviolet absorption spectra of the bromomethanes," J. Chem. Phys. 62, 848-857 (1975). http://www3.hi.is/~agust/rannsoknir/papers/jcp062-848-75.pdf Comments: Extinction coefficients read at 0.25-, 0.5, and 1-nm intervals from Fig. 6 and converted to absorption cross sections (conversion factor 3.8235x10-21).

  5. Grein pöntuð (sjá slide 8) 020311:

  6. G.C. Causley and B.R. Russell, "Vacuum ultraviolet absorption spectra of the bromomethanes," J. Chem. Phys. 62, 848-857 (1975). Spectrum from paper and digitised spectrum from database superimposed:

  7. Absorption cross section Ionization limit 83962.3 cm-1 cm-1 agust,heima,...CH2Br2/PXP-010311ak.pxp; Lay: 0, Gr:0

  8. Abs. cross section Dye: C503 Predictions: http://notendur.hi.is/agust/rannsoknir/rempi/cf3br/Bromine Lines-080910ks.docBr atomic Lines Broken lines: from 2P1/2solid lines: from 2P3/2 http://notendur.hi.is/agust/rannsoknir/papers/jpcA114-9991-10.pdfPredictions:C atomic lines 10.03.11m 09.03.11l 07.03.11j 08.03.11k Ionization limit 83962.3 cm-1 04.03.11a 05.03.11i 03.03.11b 02.03.11c 01.03.11d 28.02.11e 25.02.11f REMPI scans for C503 24.02.11g 23.02.11h 2hv/cm-1 See footnotes below: agust,heima,...CH2Br2/PXP-020311ak.pxp ; Lay:1, Gr:1; updated 130311

  9. Dat for C503: Footnotes:m(100311):ftp://130.208.167.52/Report/REMPI%20REPORT/20110310.html l(090311):ftp://130.208.167.52/Report/REMPI%20REPORT/20110309.html k(080311): ftp://130.208.167.52/Data/CH2Br2/20110308/readme.txt ; lot fo Br atomic linesftp://130.208.167.52/Report/REMPI%20REPORT/20110308.html ; Br atomic lines j(070311):ftp://130.208.167.52/Data/CH2Br2/20110307/readme.txt ;Br,H,CH,CH2 spectra in 82120-83028; Br atomic line in 82000-82140 ftp://130.208.167.52/Report/REMPI%20REPORT/20110307.html ; CH in 81760-81900 i(050311):ftp://130.208.167.52/Report/REMPI%20REPORT/20110305.html ; 79500-79360 no good. a (040311): ftp://130.208.167.52/Data/CH2Br2/20110304/readme.txt & Clear C+ REMPI spectrumftp://130.208.167.52/Report/REMPI%20REPORT/20110304.html b(030311):ftp://130.208.167.52/Data/CH2Br2/20110303/readme.txt ; Br atomic lines observedftp://130.208.167.52/Report/REMPI%20REPORT/20110303.html c( 020311): ftp://130.208.167.52/Report/REMPI%20REPORT/20110302.html d(010311): ftp://130.208.167.52/Data/CH2Br2/20110301/readme.txt : NO mention about observation of C atomic lines(?)ftp://130.208.167.52/Report/REMPI%20REPORT/20110301.html e( 280211): ftp://130.208.167.52/Data/CH2Br2/20110228/readme.txt ; strong Br atomic line seen f(250211):ftp://130.208.167.52/Data/CH2Br2/20110225/readme.txt : C atomic line seen; Br atomic line seenftp://130.208.167.52/Report/REMPI%20REPORT/20110225.html g(240211):ftp://130.208.167.52/Data/CH2Br2/20110224/Readme.txt ftp://130.208.167.52/Report/REMPI%20REPORT/20110224.html h(230211): ftp://130.208.167.52/Data/CH2Br2/20110223/Readme.txtftp://130.208.167.52/Report/REMPI%20REPORT/20110223.html

  10. Abs. cross section Dye: C503 Predictions: http://notendur.hi.is/agust/rannsoknir/rempi/cf3br/Bromine Lines-080910ks.docBr atomic Lines Broken lines: from 2P1/2solid lines: from 2P3/2 http://notendur.hi.is/agust/rannsoknir/papers/jpcA114-9991-10.pdfPredictions:C atomic lines Dye: R540 Group of C atomic lines Ionization limit 83962.3 cm-1 Weak signals 18.03.11e 17.03.11d 16.03.11c Weak signals 15.03.11b 14.03.11a Horisontal lines: REMPI scans (see also slide above) 2hv/cm-1 See footnotes below: agust,heima,...CH2Br2/PXP-020311ak.pxp ; Lay:1, Gr:1; updated 1970311

  11. Footnotes:a(140311; dye:R540): ftp://130.208.167.52/Report/REMPI%20REPORT/20110314.html b(15.03.11; dye:R540):ftp://130.208.167.52/Report/REMPI%20REPORT/20110315.html c(16.03.11; dye:R540):ftp://130.208.167.52/Report/REMPI%20REPORT/20110316.html d(17.03.11; dye:R540): ftp://130.208.167.52/Report/REMPI%20REPORT/20110317.html e(18.03.11; dye:R540): ftp://130.208.167.52/Report/REMPI%20REPORT/20110318.html

  12. Comment (020311): • It will be interesting to see if there is a correlation between the CH2+, CH+, C+. • ...spectra and the absorption spectrum shown above. Have a look at this!:

  13. Absorption cross section Absorption spectrumG.C. Causley and B.R. Russell, J. Chem. Phys. 62, 848-857 (1975). Threshold for C*(1D2) + 2hv -> C+ + e- 80625.27 cm-1 See: our CH3Br paper Page 9994 7s(b1) d=3.01 C+ REMPI spectra from 040311:c20110_20145 to c20170_20205 Peak at 80663 cm-1 2hv/cm-1 agust,heima,...CH2Br2/PXP-050311ak.pxp; lay:0; Gr:1

  14. Comments: • The C+ REMPI peak fits exactly the absorption peak • for CH2Br2 corresponding to transition to the 7s(b1) Rydberg state according to • the paper by Causley and Russel (C&R) • (http://www3.hi.is/~agust/rannsoknir/papers/jcp062-848-75.pdf) • I wonder if the Rydberg state assignment by C&R is correct(?). It is more likely that • a (2+n)REMPI spectrum is due to a resonance transition to a p-Rydberg state due selection rules! • Are peaks also found at this position (see above) for the CH2+ and CH+ ions? • We desperatelly need “Dye power curves” along with the absorption spectrum • Most likely C is formed after 2hv excitation to a Rydberg state by channels such as: • CH2Br2** -> 2HBr + C OR • CH2Br2** -> H2 + C + Br2 • NB!: If the former channel is occuring we might see HBr (2+n) REMPI! ERGO: Look for HBr REMPI in the CH2Br2 data. updated 060311

  15. agust,heima,...CH2Br2/C REMPI-130411jl.pxp

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