CH2Br2: 1) Absorption2) REMPI scans: overview (slides 12-15)3) C+ REMPI vs absorption spectrum

agust,www,....ch2br2/PPT-010311ak.pptagust,heima,...CH2Br2/PXP-010311ak.pxpagust,heima,...CH2Br2/PXP-020311ak.pxpagust,heima,...CH2Br2/PXP-050311ak.pxpagust,heima,...CH2Br2/C REMPI-130411jl.pxp

Searched for “CH2Br2 absorption” in Google:

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Structure Author(Year) Temperature Wavelength range Information

CH2Br2 CausleyRussell(1975) 298K 110-180nm(0.25,0.5,1nm) Details | Data

nm

Details

Structure: CH2Br2

Name: dibromomethane

Author(Year): CausleyRussell(1975)

Temperature: 298K

Wavelength range: 110-180nm(0.25,0.5,1nm)

Bibliography: G.C. Causley and B.R. Russell, "Vacuum ultraviolet absorption spectra of the bromomethanes," J. Chem. Phys. 62, 848-857 (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 3.8235x10-21).

http://www3.hi.is/~agust/rannsoknir/papers/jcp062-848-75.pdf

Grein pöntuð (sjá slide 8) 020311:

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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:

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Ionization limit83962.3 cm-1

cm-1

Absorptioncross section

agust,heima,...CH2Br2/PXP-010311ak.pxp; Lay: 0, Gr:0

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Ionization limit83962.3 cm-1

Abs.cross section

23.02.11h24.02.11g

25.02.11f

28.02.11e

01.03.11d

REMPI scansfor C503

agust,heima,...CH2Br2/PXP-020311ak.pxp ; Lay:1, Gr:1; updated 130311

03.03.11b

02.03.11c

04.03.11a

See footnotes below:

2hv/cm-1

http://notendur.hi.is/agust/rannsoknir/papers/jpcA114-9991-10.pdf

Predictions:C atomic lines

05.03.11i

Predictions: http://notendur.hi.is/agust/rannsoknir/rempi/cf3br/Bromine Lines-080910ks.doc

Br atomic LinesBroken lines: from 2P1/2

solid lines: from 2P3/2

07.03.11j

08.03.11k

09.03.11l

10.03.11m

Dye: 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 lines ftp://130.208.167.52/Report/REMPI%20REPORT/20110308.html ; Br atomic linesj(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 81760-81900i(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 spectrum ftp://130.208.167.52/Report/REMPI%20REPORT/20110304.htmlb(030311): ftp://130.208.167.52/Data/CH2Br2/20110303/readme.txt ; Br atomic lines observed ftp://130.208.167.52/Report/REMPI%20REPORT/20110303.htmlc( 020311): ftp://130.208.167.52/Report/REMPI%20REPORT/20110302.htmld(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.htmle( 280211): ftp://130.208.167.52/Data/CH2Br2/20110228/readme.txt ; strong Br atomic line seenf(250211): ftp://130.208.167.52/Data/CH2Br2/20110225/readme.txt : C atomic line seen; Br atomic line seen ftp://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.htmlh(230211): ftp://130.208.167.52/Data/CH2Br2/20110223/Readme.txt ftp://130.208.167.52/Report/REMPI%20REPORT/20110223.html

Dat for C503:

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Ionization limit83962.3 cm-1

Abs.cross section

Horisontal lines: REMPI scans (see also slide above)

agust,heima,...CH2Br2/PXP-020311ak.pxp ; Lay:1, Gr:1; updated 1970311See footnotes below:

2hv/cm-1

http://notendur.hi.is/agust/rannsoknir/papers/jpcA114-9991-10.pdf

Predictions:C atomic lines

Predictions: http://notendur.hi.is/agust/rannsoknir/rempi/cf3br/Bromine Lines-080910ks.doc

Br atomic LinesBroken lines: from 2P1/2

solid lines: from 2P3/2

Dye: C503

Dye: R540

14.03.11a

15.03.11b

16.03.11c

Weak signals

Group ofC atomic lines

17.03.11d

Weak signals

18.03.11e

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.htmlc(16.03.11; dye:R540):ftp://130.208.167.52/Report/REMPI%20REPORT/20110316.htmld(17.03.11; dye:R540):ftp://130.208.167.52/Report/REMPI%20REPORT/20110317.htmle(18.03.11; dye:R540):ftp://130.208.167.52/Report/REMPI%20REPORT/20110318.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!:

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Absorptioncross section

C+ REMPI spectra from040311:

c20110_20145 toc20170_20205

Peak at 80663 cm-1

Absorption spectrumG.C. Causley and B.R. Russell, J. Chem. Phys. 62, 848-857 (1975). 7s(b1) =3.01

2hv/cm-1

agust,heima,...CH2Br2/PXP-050311ak.pxp; lay:0; Gr:1

Threshold forC*(1D2) + 2hv -> C+ + e-

80625.27 cm-1

See: our CH3Br paperPage 9994

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

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