eirík´s project(?) ch 3 i: agust,www,...rempi/ch3i/ppt-050112ak.ppt ( )

Eirík´s project(?)

CH3I:

agust,www,...rempi/ch3i/PPT-050112ak.ppt(https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PPT-050112ak.ppt )agust,heima,...REMPI/CH3I/PXP-050112ak.pxp

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PXP-230112ak.pxp (energetics and abs. spectrum)

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/XLS-230112ak.xls (energetics)

1)compound: availability and physical properties2)Absorption spectra on www3)Papers4)Energetics(?)

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PPT-050112ak.ppt

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PXP-230112ak.pxp

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/XLS-230112ak.xls

Eiríks project

1) CH3I:

Svana´s e-mail, 071211:

http://en.wikipedia.org/wiki/Methyl_iodide :

liquid

Vapor pressure:

CRC: 1 mm 10 40 100 400 760 mp

S -45.8oC -24.2 -7.0 +25.3 42.4 -64.4

Vapor pressure = 100 Torr for -7 oC

See cooling baths: http://www.chem.orst.edu/carter/Baths.html

http://en.wikipedia.org/wiki/Methyl_iodide

http://www.chem.orst.edu/carter/Baths.html

ATH 1

ATH 2

500

400

300

200

100

0

x10-1

8

300250200150

agust,heima,...REMPI/CH3I/PXP-050112ak.pxp; Lay:0, Gr:0

ATH 1https://notendur.hi.is/agust/rannsoknir/papers/CH3X/cp331-232-07.pdf

(2007)

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/cp331-232-07.pdf

agust,heima,...REMPI/CH3I/PXP-050112ak.pxp; Lay:0, Gr:0

2.5

2.0

1.5

1.0

0.5

0.0

-0.5

x10-1

8

300280260240

ATH 1

150

100

50

0

x10-1

8

240220200180160140120

ATH 2

agust,heima,...REMPI/CH3I/PXP-050112aka.pxp; Lay:0, Gr:0

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/cp365-109-09.pdf


Absorption references:





Absorption references: https://notendur.hi.is/agust/rannsoknir/papers/CH3X/cp331-232-07.pdf



Absorption references: https://notendur.hi.is/agust/rannsoknir/papers/CH3X/cp331-232-07.pdf

See tables 4-7 inThe paper



Check REMPI work-by Donovan et al.-references in CH3Br REMPI paper etc.

With repect to Rydberg state structure.

Papers: See also Eirik´s folder

Rydberg states: https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp99-836-93.pdf RESONANCE-ENHANCED MULTIPHOTON IONIZATION PHOTOELECTRON-SPECTROSCOPY ON NANOSECOND AND PICOSECOND TIME SCALES OF RYDBERG STATES OF METHYL-IODIDE

Abstract: Rydberg states of methyl iodide have been investigated using resonance enhanced multiphoton ionization in combination with photoelectron spectroscopy with nanosecond and picosecond laser pulses. The study of the ns (6 less-than-or-equal-to n less-than-or-equal-to 10) Rydberg states in two-, three-, and four-photon excitations has resulted in an unambiguous identification of state [1] in the 7s and 8s Rydberg states. As a consequence, it is concluded that the transition to 6s[1] in two- and three-photon excitations is anomalously weak. The application of photoelectron spectroscopy to identify the electronic and vibrational nature of a resonance has led to a major reinterpretation of the excitation spectrum of the 6p Rydberg state in two-photon excitation. In many of the recorded photoelectron spectra anomalous electrons are observed, which derive from a one-photon ionization process. This process is suggested to find its origin in the mixing of 6p and 7s character into higher-lying Rydberg states. The major difference between resonance enhanced multiphoton ionization photoelectron spectroscopy with nanosecond and picosecond lasers is found in a less effective dissociation of the molecule in the picosecond experiments.

...Ry states, state mixing, vibr. Freq. Modes, (2+1)REMPI spectra and assignments of Rydb. states

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp99-836-93.pdf

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/cpl156-151-89.pdf


(2+1)REMPI..3p Ry



https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jpc86-60-82.pdf

Shows 1) mass spectra and 2) energetics



Bond energies, ..


1) https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/cpl516-23-11.pdf Isotopic effect in the (2+1) REMPI spectra of (13)C-substituted methyl iodide for UV selective dissociation

To investigate a possible means of achieving isotopic enrichment of methyl iodide (CH(3)I), we studied the 6s Rydberg states of (13,12)CH(3)I by (2+1) resonance-enhanced multiphoton ionization. For 3; 3(1)(0) band (v3 hot band) excitation ( at a full width at half maximum of 14 cm (1)), we observed a well-resolved isotope shift of +16 cm (1). The band shape, which has a broad shoulder on the red side and an abrupt decrease on the blue side, indicates that this resonance is ideal for enriching the concentration of the desired lighter isotope (the isotopomer). (C) 2011 Elsevier B.V. All rights reserved.

2) https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jms257-200-09.pdf Photoelectron imaging of 8p Rydberg states of atomic iodine following methyl iodide A-band decomposition

Photoelectron imaging technique has been applied to study (2 + 1) REMPI of atomic iodine through 8p Rydberg states around 253 nm. Full three-dimensional state-specific speed and angular distributions of the photoelectrons were recorded. The branching ratios among the different I(+) levels revealed that the perturbation on ((3)P(2))8p series is particularly large among the ((3)P(2))np series. The violation of core-conserving ionization is attributed to the interactions between the ((3)P(2))8p and ((1)D(2))6p series. The photoelectron angular distributions were found to be well characterized by P(2)(cos theta) and P(4)(cos theta). A relatively high positive beta(2) and a relatively low beta(4) observed in (2 + 1) REMPI process indicated that the ionization process can be approximately considered as single-photon ionization via the weakly aligned ((3)P(2))8P intermediate states. (C) 2009 Elsevier Inc. All rights reserved.

Less useful but new papers:


https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jms257-200-09.pdf

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jams2-93-11.pdf

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jams2-93-11.pdf

Now we need to look at the energetics, analogous to that for CH2Br2:http://www3.hi.is/~agust/rannsoknir/rempi/ch2br2/PPT-010211ak.ppt(See slides 6 -11)

http://www3.hi.is/~agust/rannsoknir/rempi/ch2br2/PPT-010211ak.ppt


Fig 10:


NIST

IE:

76945.25 cm-1

http://www.sciencedirect.com/science/article/pii/S0009261401008648

19195.9852 cm-1


CH3I D:

2.38eV http://www.sciencedirect.com/science/article/pii/S0009261401008648 19195.9874cm-1 Factors:

f1: 8.36E+01cm-1 / (kJ mol-1)

f2: 3.50E+02cm-1 / (kcal mol-1) f3: 8065.54093cm-1/eV E(6s) = 54633.46cm-1 E(4P;5s)+D= 73829.45cm-1 IE(CH3I)= 9.54eV NIST IE(CH3I)= 76945.26047cm-1 IE(I)= 84295.1cm-1 http://physics.nist.gov/cgi-bin/ASD/energy1.pl E(S/O;I)= 7602.97cm-1 http://physics.nist.gov/cgi-bin/ASD/energy1.pl

E(CH3+I*(1/2))= 26798.95741cm-1 E(CH3+I+ + e)= 103491.0874cm-1 IE(CH3) = 9.84eV 79364.92275cm-1 NIST E(CH3

+ + e + I) 98560.91016cm-1 EA(I) = 3.0590463eV http://en.wikipedia.org/wiki/Electron_affinity_%28data_page%29 24672.8631cm-1E(CH3

+ + I-)= 73888.04703cm-1 E(I+)-E(I*)= 76692.13cm-1




http://webbook.nist.gov/cgi/cbook.cgi?ID=C10035106&Units=SI&Mask=20

http://physics.nist.gov/cgi-bin/ASD/energy1.pl




http://en.wikipedia.org/wiki/Electron_affinity_(data_page)

http://en.wikipedia.org/wiki/Electron_affinity_(data_page)


100

80

60

40

20

0

x10

3

4.03.53.02.52.01.51.0

CH3 + I; 19195.9874

CH3 + I*; 26798.95741

CH3 + I**(min); 73829.45

CH3+ + e + I; 98560.91016

CH3 + I+ + e; 103491.0874

CH3I

CH3I+ + e; 76945.26047

cm-1



140

120

100

80

60

40

20

0

x10

3

43210


CH3 + I; 19195.9874

CH3 + I*; 26798.95741

CH3 + I**(min); 73829.45

CH3+ + e + I;

98560.91016

CH3 + I+ + e; 103491.0874

CH3I

CH3I+ + e; 76945.26047

Abs. spectrum

(1)

(2)

(3)

(4)(n) = number of photons

70000

55000


71

70

69

68

67

66

65

x10

3

1.61.41.21.00.80.60.40.20.0

CH3+ + e + I;

65707.27 cm-1

..threshold hv(Laser)=16426.82 (608.7606 nm)

CH3 + I+ + e; 68994.06 cm-1..threshold:hv(Laser) = 17248.51(579.7601 nm)


70000 cm-1


REMPI spectra and assignments from the literature:

n:

222

22222222

s -States and spectraobserved inTwo-photon REMPI


n = number of resonance excitationphotons


n:

222

22222222

s -States and spectraobserved inTwo-photon REMPI



:58000 64000

2hv


p -States and spectraobserved inTwo-photon REMPI


80

75

70

65

60

55

50

x10

3

1.41.21.00.80.60.40.20.0

p states spectraobservedin (2+n)REMPI

s states spectraobservedin (2+n)REMPI


Ca. Spectral region forR590!66640-69480


80

75

70

65

60

55

50

x10

3

1.41.21.00.80.60.40.20.0


s states spectraobservedin (2+n)REMPI


64

00

05

80

00


64

63

62

61

60

59

58

x103

1.51.00.50.0

64

00

05

80

00

62

00

06

00

00


Comparison of absorption and REMPI spectra:



73.0

72.9

72.8

72.7

72.6

72.5

x103

1.81.61.41.21.00.80.60.40.2

72900

72500

74.6

74.4

74.2

74.0

73.8

73.6

73.4

73.2

x103

1.51.00.5

140

120

100

80

60

40

20

0

x10

3

43210

CH3 + I; 19195.9874

CH3 + I*; 26798.95741

CH3 + I**(min); 73829.45

CH3+ + e + I;

98560.91016

CH3 + I+ + e; 103491.0874

CH3I

CH3I+ + e; 76945.26047

Abs. spectrum

(1)

(2)

(3)

(4)(n) = number of photons

70000

55000


x100

The A-band


80

70

60

50

40

30

x10

3

1.41.21.00.80.60.40.20.0

CH3I+ + e; 76945.26047

Abs. spectrum

(1)

(2)

(n) = number of photons

70000

55000

x100


The A-bandn *(C-I)

65707.27 cm-1)

68994.06 cm-1


5000

4000

3000

2000

1000

0

69.569.068.568.067.567.0x10

3

CH3+ 1D REMPIuncorrected

Absorption spectrum

2hv

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/Experiment-260112vhwak.pxp

30

25

20

15

10

5

x10

3

250200150100500

C+

CH+

CH2+

CH3+

I+

I2+

CH3I+

Mass Spectrum Calibration

Mass Spectrum calibration

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/Experiment-260112vhwak.pxp

??? cm-1

pnt

IDEA!: an I2+ mass peak observed could be due to a molecular dimer

(CH3I)2

ERGO: let´s see the effect of less cooling, i.e. 1)less % argon 2) less backing pressure

. Let´s check the literature

Literature:

1) http://www.chemthes.com/entity_datapage.php?id=1851 :Van der Waals complexes

2) http://jcp.aip.org/resource/1/jcpsa6/v97/i1/p189_s1?isAuthorized=no https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp97-189-92.pdf :“Ground electronic state I2 is formed from the photolysis of methyl iodide dimers”

3) Sjá meira neðar

See example for effect of buffer gas (rare gas) on jet cooling next slide:

http://www.chemthes.com/entity_datapage.php?id=1851

http://jcp.aip.org/resource/1/jcpsa6/v97/i1/p189_s1?isAuthorized=no


Largest molecular density=

molecular beam

Small molecular density=molecular diffusion

medium molecular density

Skimmer;Not used in our case

Beam axis

http://www.nature.com/nphys/journal/v4/n8/box/nphys1031_BX1.html :

http://www.nature.com/nphys/journal/v4/n8/box/nphys1031_BX1.html

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jppbA100-9-96.pdf :

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jppbA100-9-96.pdf

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jpc100-11559-96.pdf :

http://jcp.aip.org/resource/1/jcpsa6/v97/i1/p189_s1?isAuthorized=no &https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp97-189-92.pdf :


http://jcp.aip.org/resource/1/jcpsa6/v97/i1/p189_s1?isAuthorized=no


1 mm 10 40 100 400 760 P Torr

S -45.8 -24.2 -7 25.3 42.4 t/oC227.35 248.95 266.15 298.45 315.55 T/K

0.0043985 0.004017 0.003757 0.003351 0.003169 1/T (K-1)2.30258509 3.688879 4.60517 5.991465 6.633318 ln(p)

ln(p) 1/T (K-1)2.30258509 0.4342943.68887945 0.2710854.60517019 0.2171475.99146455 0.1669046.63331843 0.150754

6

5

4

3

0.400.350.300.250.20

1/T (K-1)

Ln(p)

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/XLS-270112ak.xls https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PXP-270112ak.pxp

ln(p) vs 1/T is nonlinear suggesting less importance of dimers as temperature rizes.



This could mean that CH3I dimers are even formed in the vapour above the trapwhen cooled with CCl4 slash bath (-23oC)!!

--further suggesting that it might be better to use less cooling for the trap:

How about to use cold water only (analogous to that used for CH2Br2

earlier) ???

10

8

6

4

2

0

x10

3

70.069.569.068.568.0x10

3



Absorption spectrum

2hv

No clear correspondance between REMPI and absorption spectra in this region


200

150

100

50

0

x10

3

70.0069.9569.9069.8569.8069.7569.70x10

3


Absorption spectrum

2hv

What on earth is that???



20

15

10

5

0

x10

3

70.0069.9569.9069.8569.8069.7569.70x10

3

CH3+ 1D REMPIuncorrectedAbsorption

spectrum

2hv

This looks like P, Q and R brances

Of symmetric top: seen next slide


= 19.16..18.36..16.8 19.84 19.84 19.84


IR róf topsamhverfra sameinda /IR spectra for symmetric top molecules:

CH3I:

Topsamhv.

http://notendur.hi.is/agust/kennsla/ee10/eeb/PPT/IR%20rof.ppt:

B: Fundamentals of Molecular Spectroscopy eftir C.N. Banwell og E.M. McCash, (McGraw-Hill, 4. útg. 1994)

http://notendur.hi.is/agust/kennsla/ee10/eeb/PPT/IR%20rof.ppt

1.0

0.8

0.6

0.4

0.2

0.0

x10

6

17.517.417.317.217.117.016.9x10

3

I+

CH3+

C+

CH3I Spectra, not power correction yet.

800

600

400

200

x103

17.45517.45017.44517.44017.435x10

3

I+

CH3+

C+


Are these all iodine atomic lines? What transitions are these, Eiríkur?


hv(laser)


50

40

30

20

10

0

x103

17.4517.4017.35x10

3

I+

CH3+

C+


Same molecular peak seen in the I+ and CH3+ spectra

hv(laser)


C atomic lines Small but significantpeak


140

120

100

80

60

40

20

0

x103

70.570.069.569.068.568.0x10

3

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PXP-250312ak.pxp og

140

120

100

80

60

40

20

0

x103

70.0570.0069.9569.9069.8569.8069.7569.70x10

3

69852.92828 cm-1

ftp://130.208.167.52/Data/CH3I/Calibartion Work/calibration/ allt I cal, 16220_17510 funky17540_17650-210312.pxp

CH3+ REMPI


ftp://130.208.167.52/Data/CH3I/Calibartion%20Work/calibration/allt%20I%20cal,%2016220_17510%20funky17540_17650-210312.pxp

140

120

100

80

60

40

20

0

x103

70.570.069.569.068.568.0x10

3

40

30

20

10

0

x103

70.7070.6870.6670.6470.6270.6070.5870.5670.54x10

3

70626.462 cm-1



773.5337 cm-1

8.408

8.4

CH3+ REMPI



16

14

12

10

8

6

4

2

0

x106

72706866x10

3



I+ REMPI



Symmetric top:

http://www.hi.is/~agust/kennsla/ee05/ee405/rotst.ppt

https://notendur.hi.is/agust/kennsla/ee10/ees10/snthrep.htm

http://www.hi.is/~agust/kennsla/ee05/ee405/rotst.ppt

https://notendur.hi.is/agust/kennsla/ee10/ees10/snthrep.htm

http://webbook.nist.gov/cgi/cbook.cgi?ID=C2229074&Units=SI&Mask=800#Electronic-Spec:

140

120

100

80

60

40

20

0

x10

3

70.0570.0069.9569.9069.8569.8069.7569.70x10

3

69852.92828 cm-1

OUR CH3+ REMPI spectrum

At 69852.9 is

Due to CH3 !!!!

Check this reference

http://webbook.nist.gov/cgi/cbook.cgi?ID=C2229074&Units=SI&Mask=800#Electronic-Spec

https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp89-3986-88.pdf :


https://notendur.hi.is/agust/rannsoknir/papers/CH3X/CH3I/jcp89-3986-88.pdf : 140

120

100

80

60

40

20

0

x10

3

70.0570.0069.9569.9069.8569.8069.7569.70x10

3

69852.92828 cm-1

Ours

NB!:

K = 0



Ground state

Excited state

Coupling terms

NB!:

K = 0

..but what about this spectrum:

40

30

20

10

0

x103

70.7070.6870.6670.6470.6270.6070.5870.5670.54x10

3

It must be because of CH3There is no reported electronic state for CH3 at this wavenumberThe spacing of 773.5 cm-1 between the two CH3+ spectra suggests that it could be A vibrationally excited state

70626.462 cm-1773.5337

cm-1

Could be the a2 2 (OPLA)vibrational mode

Let´s check references

out‐of‐plane large amplitude (OPLA)-mode

= umbrella modes


NB!: OPLA modes can be significantly different for excitede states than forThe ground state, thus:

NIST:


...but these seem, generally to be the lowest numbers

7

6

5

4

3

2

1

0

70.069.969.869.7x10

3

O

P Q R

S

Our spectrum simulatedfor parameters in


Calculations were performed in


https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/XLS-020412ak.xls 69852.92828 cm-1

40

30

20

10

0

x103

70.7070.6870.6670.6470.6270.6070.5870.5670.54x10

3

Since the Q branch in the 70626.462 cm-1

system is degraded to red (low wavenumber)opposide of what is found for the 69852.92828 cm-1

system (slide 72) it suggest thatB´< B´´ opposide of what is found for the 69852.92828 cm-1 sysem (see slide 68) whereB´= 9.90 cm-1 and B” = 9.577..cm-1

70626.462 cm-1

First attempts to simulate the vibrationally excited band of CH3:

8

6

4

2

0

70.8570.8070.7570.7070.6570.6070.5570.50x10

3

9.57789 = B”0.0007699 =DN” -0.0001358 =DNK”9 =B´0.00107 =DN´-0.00212 =DNK´70627.2 “=0-0.088 =C0 =DK

RQ

S

PO

K = 0

70626.462 cm-1

https://notendur.hi.is/agust/rannsoknir/rempi/ch3i/PXP-020412aka.pxp

eirík´s project(?) ch 3 i: agust,www,...rempi/ch3i/ppt-050112ak.ppt ( )

Documents

s rydberg states

p rydberg state

ry states

rydberg state structure

rempi spectra

photon ionization process

pd resonance

eiriks folderrydberg