1. CF3Br
agust,www,....cf3br/PPT ak.ppt
agust,heima,....Sept10/XLS ak.xls
agust, heima,...PXP ks/Leiðrétt ks ak.pxp (CF3+)
agust,heima,... PXP ks/Br 1D-REMPImW ks ak.pxp (Br+)

2. Bond dissociation for CF3Br revisited:
The value used in
( cm-1)is based on a paper from 1966 (see slide 3 in
The value used by Suto and Lee (JCP, 79(3), 1127, (´83) (see: page 1131), based on
Thermochemical data (Okabe, “Photochemistry of small molecules”, (1978)) is
2.98 eV (* cm-1/eV) = cm-1 which is is significantly lower.
CF3+ + Br- threshold revisited:
This affects the estimate of the CF3+ + Br- threshold:
E(CF3+ + Br-) = = cm-1
agust,heima,....Sept10/XLS ak.xls

3. CF3* + Br thresholds:
Suto and Lee (JCP, 79(3), 1127, (´83) (see: page 1132):
UV spectrum: eV = cm-1
Vis spectrum: eV = cm-1

4. UV spectrum: 75493.46 cm-1 Vis spectrum: 75332.15 cm-1
CF3* + Br thresholds
agust, heima,...PXP ks/Leiðrétt ks ak.pxp

5. CF3* + Br thresholds UV spectrum: 75493.46 cm-1
Vis spectrum: cm-1
agust,heima,... PXP ks/Br 1D-REMPImW ks ak.pxp

6. Now let´s look at the energetics with respect to CF3+ formation via CF3* formation
(see fig. Next slide)

7. (Semi) schematic energy figure: E/cm -1 CF3 + + Br 96947.79 cm-1
CF3Br+ + e-
91980 cm-1
cm-1
CF3 * + Br
/ cm-1
CF Br-
cm-1
{CF3+Br-}?
Ion-pair state?
ca cm-1
CF3 + Br
CF3Br(?)
R(CF3 –Br)
Agust,heima,...CF3Br/Sept10/PXP ak.pxp; Layout::0, Graph: 0, Table::0

8. Possible dissociation mechanism(1):
Ry -> Ion-pair -> CF3+ + Br- formation
E/cm -1
CF Br
cm-1
CF3Br+ + e-
91980 cm-1
(1)
cm-1
CF3 * + Br
CF Br-
/ cm-1
CF Br-
cm-1
{CF3+Br-}?
Ion-pair state?
ca cm-1
CF3 + Br
CF3Br(?)
R(CF3 –Br)
Agust,heima,...CF3Br/Sept10/PXP ak.pxp; Layout::0, Graph: 0, Table::0

9. Possible dissociation mechanism(2): Ry -> CF3* + Br dissociation
E/cm -1
CF Br
cm-1
CF3Br+ + e-
91980 cm-1
(2)
cm-1
CF3 * + Br
/ cm-1
CF Br-
cm-1
{CF3+Br-}?
Ion-pair state?
ca cm-1
CF3 + Br
CF3Br(?)
R(CF3 –Br)
Agust,heima,...CF3Br/Sept10/PXP ak.pxp; Layout::0, Graph: 0, Table::0

10. This brake in CF3+ intensity could be because
UV spectrum: cm-1
Vis spectrum: cm-1
This brake in CF3+ intensity could be
because
-for 2hv < cm-1 only channels
occurs (i.e. CF3Br** ->-> CF3+ + Br-)
b) for hv > cm-1, competition
Between (1)(direct CF3+ formation)
and (2)(CF3* formation)
However based on PD data the observed
CF3+ signal all over most probably is
mainly due to (1) (i.e. direct CF3+ formation)
CF3* + Br thresholds
agust, heima,...PXP ks/Leiðrétt ks ak.pxp

11. Now let´s compare the “spin-orbit splitting” structure observed in the fluorescenec
Spectrum for CF3Br and mentioned
by Suto and Lee (JCP, 79(3), 1127, (´83) (see: page 1132), i.e.

12. Fluorescence maxima (a) (b) (c) (d)
agust, heima,...PXP ks/Leiðrétt ks ak.pxp

13. The fluorescenec maxima do not match CF3+ signal maxima
The fluorescenec maxima do not match CF3+ signal maxima. On the contrary
It looks more as if the maxima are in between peaks or close to minima in
CF3+ signals (peaks (a)- (c). This could further indicate that there is a competition
between channels (1) and (2)! :
2) 11.7 eV
1) 11.4 eV
Try to search for systematic spacing between peaks close to 0.3 and 0.46 eV:

14. Now let´s look at quantum defects:
0.3 eV
0.46 eV
0.2 eV
0.264 eV
0.35 eV
1) En = cm-1 =
9.24 eV
2) En = =
9.24 eV
agust, heima,...PXP ks/Leiðrétt ks ak.pxp

15. = n – sqrt(R/(EI-En)); n = 5, R = 13.61 eV
1) d = 2.5
2) d = 2.5
Which is what one might expect for d for R-Br, p orbitals (and better value than that
given by Eden et al. ( )
of 2.71) :
See: (CH3Br)
and
(Br2)
Ergo: I conclude that the peaks at 1) just below cm-1 and 2) ca cm-1
are due to transitions to the Rydberg states:
1) [CF3Br+ (X 2E3/2)]c 5p and
2) [CF3Br+ (X 2E1/2)]c 5p
Possibly the peak near cm-1 is due to transition to [CF3Br+ (A 2E1/2)]c 5p

16. but what about the “peak” just below 77000 cm-1, i
...but what about the “peak” just below cm-1, i.e ca 1000 cm-1 above
The peak for [CF3Br+ (X 2E3/2)]c 5p . Could that be a vibrational
Band?
NIST =>
ERGO: yes it could indeed be a vibrational band such as CF3 stretching(?)