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

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StructureAuthor(Year)TemperatureWavelength rangeInformation CH2Br2CausleyRussell(1975)298K nm(0.25,0.5,1nm)DetailsDetails | DataData nm

Details Structure:CH2Br2 Name:dibromomethane Author(Year):CausleyRussell(1975) Temperature:298K Wavelength range: nm(0.25,0.5,1nm) Bibliography: G.C. Causley and B.R. Russell, "Vacuum ultraviolet absorption spectra of the bromomethanes," J. Chem. Phys. 62, (1975). Comments: Extinction coefficients read at 0.25-, 0.5, and 1-nm intervals from Fig. 6 and converted to absorption cross sections (conversion factor x ).

Grein pöntuð (sjá slide 8) :

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

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

Ionization limit cm-1 Abs. cross section h g f e d REMPI scans for C503 agust,heima,...CH2Br2/PXP ak.pxp ; Lay:1, Gr:1; updated b c a See footnotes below: 2hv/cm Predictions: C atomic lines i Predictions: Lines ks.doc Br atomic Lines ks.doc Lines Broken lines: from 2 P 1/2 solid lines: from 2 P 3/ j k l m Dye: C503

Footnotes: m(100311): ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Report/REMPI%20REPORT/ html l(090311): ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Report/REMPI%20REPORT/ html k(080311): ftp:// /Data/CH2Br2/ /readme.txt ; lot fo Br atomic lines ftp:// /Report/REMPI%20REPORT/ html ; Br atomic linesftp:// /Data/CH2Br2/ /readme.txtftp:// /Report/REMPI%20REPORT/ html j(070311): ftp:// /Data/CH2Br2/ /readme.txt ;Br,H,CH,CH2 spectra in ; Br atomic line in ftp:// /Data/CH2Br2/ /readme.txt ftp:// /Report/REMPI%20REPORT/ html ; CH in ftp:// /Report/REMPI%20REPORT/ html i(050311): ftp:// /Report/REMPI%20REPORT/ html ; no good.ftp:// /Report/REMPI%20REPORT/ html a (040311): ftp:// /Data/CH2Br2/ /readme.txt & Clear C+ REMPI spectrum ftp:// /Report/REMPI%20REPORT/ html ftp:// /Data/CH2Br2/ /readme.txtftp:// /Report/REMPI%20REPORT/ html b(030311): ftp:// /Data/CH2Br2/ /readme.txt ; Br atomic lines observed ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Data/CH2Br2/ /readme.txtftp:// /Report/REMPI%20REPORT/ html c( ): ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Report/REMPI%20REPORT/ html d(010311): ftp:// /Data/CH2Br2/ /readme.txt : NO mention about observation of C atomic lines(?) ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Data/CH2Br2/ /readme.txtftp:// /Report/REMPI%20REPORT/ html e( ): ftp:// /Data/CH2Br2/ /readme.txt ; strong Br atomic line seenftp:// /Data/CH2Br2/ /readme.txt f(250211): ftp:// /Data/CH2Br2/ /readme.txt : C atomic line seen; Br atomic line seen ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Data/CH2Br2/ /readme.txtftp:// /Report/REMPI%20REPORT/ html g(240211): ftp:// /Data/CH2Br2/ /Readme.txtftp:// /Data/CH2Br2/ /Readme.txt ftp:// /Report/REMPI%20REPORT/ html h(230211): ftp:// /Data/CH2Br2/ /Readme.txt ftp:// /Report/REMPI%20REPORT/ htmlftp:// /Data/CH2Br2/ /Readme.txtftp:// /Report/REMPI%20REPORT/ html Dat for C503:

Ionization limit cm-1 Abs. cross section Horisontal lines: REMPI scans (see also slide above) agust,heima,...CH2Br2/PXP ak.pxp ; Lay:1, Gr:1; updated See footnotes below: 2hv/cm Predictions: C atomic lines Predictions: Lines ks.doc Br atomic Lines ks.doc Lines Broken lines: from 2 P 1/2 solid lines: from 2 P 3/2 Dye: C503 Dye: R a b c Weak signals Group of C atomic lines d Weak signals e

Footnotes: a(140311; dye:R540): ftp:// /Report/REMPI%20REPORT/ html b( ; dye:R540): ftp:// /Report/REMPI%20REPORT/ html ftp:// /Report/REMPI%20REPORT/ html c( ; dye:R540): ftp:// /Report/REMPI%20REPORT/ html ftp:// /Report/REMPI%20REPORT/ html d( ; dye:R540): ftp:// /Report/REMPI%20REPORT/ html e( ; dye:R540): ftp:// /Report/REMPI%20REPORT/ html

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!:

Absorption cross section C + REMPI spectra from : c20110_20145 to c20170_20205 Peak at cm -1 Absorption spectrum G.C. Causley and B.R. Russell, J. Chem. Phys. 62, (1975). 7s(b 1 )  =3.01 2hv/cm -1 agust,heima,...CH2Br2/PXP ak.pxp; lay:0; Gr:1 Threshold for C*( 1 D 2 ) + 2hv -> C + + e cm -1 See: our CH3Br paper Page 9994

Comments: The C + REMPI peak fits exactly the absorption peak for CH 2 Br 2 corresponding to transition to the 7s(b 1 ) Rydberg state according to the paper by Causley and Russel (C&R) ( 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 CH 2 + 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: CH 2 Br 2 ** -> 2HBr + C OR CH 2 Br 2 ** -> H 2 + C + Br 2 NB!: If the former channel is occuring we might see HBr (2+n) REMPI! ERGO: Look for HBr REMPI in the CH 2 Br 2 data. updated

agust,heima,...CH2Br2/C REMPI jl.pxp