HIGH RESOLUTION INFRARED SPECTROSCOPY OF N 2 O-C 4 H 2 AND CS 2 −C 2 D 2 DIMERS MAHDI YOUSEFI S. SHEYBANI-DELOUI JALAL NOROOZ OLIAEE BOB MCKELLAR NASSER.

HIGH RESOLUTION INFRARED SPECTROSCOPY OF N2O-C4H2 AND CS2−C2D2 DIMERS

MAHDI YOUSEFI

S. SHEYBANI-DELOUI

JALAL NOROOZ OLIAEE

BOB MCKELLAR

NASSER MOAZZEN-AHMADI

Previous studies

Spectrometer

N2O-C4H2

CS2-C2D2

(CS2)2-C2D2

Summary

OUTLINE

MOTIVATION

Theoretical Structure

J. Norooz Oliaee, , Mahin Afshari , M. Dehghany, N. Moazzen-Ahmadi , A.R.W. McKellar, Journal of Molecular Spectroscopy 257 (2009) 133–136.

Experimental structure

• a/b-type band• Near parallel structure with Cs symmetry

M. Dehghany, M. Afshari, J. Norooz Oliaee, N. Moazzen-Ahmadi, and A.R.W. McKellar,Chem. Phys. Lett. 473, 26 (2009).

FB09

1

2

1

2

Quantum cascade laser (N2O-C4H2) or optical parametric oscillator (CS2-C2D2)

• Rapid scan signal averaging with background subtraction (jet on minus jet off)• Multi pass cell gives >100 traversals of laser through jet• Wavelength calibration using reference gas and etalon

Pulsed supersonic jet expansion

• Dual slit pulsed nozzle• Repetition rate: 0.5 to 2 Hz• Backing pressures ~5-20 atm• Diffusion pump (Varian VHS-10)• Backing pump (Edwards EM275)

SPECTROMETER

EXPERIMENTAL SETUP

Blue shifted 2.29 cm-1 w.r.t. N2O ν1

Rotational temperature of 2.8 K

Line-widths of 0.0025 cm-1

Cs symmetry a/b-type band

PGOPHER program is used

N2O-C4H2: OBSERVED SPECTRUM

N2O-C4H2: MOLECULAR PARAMETERS

ab-initio Calculation (DFT)

ab-initio calculation( MP2)

Experimental Value

Aʺ/MHz 4622.3 4470.8 4496.60(17)

Bʺ/MHz 1389.5 1494.5 1409.003(70)

Cʺ/MHz 1068.4 1120.1 1070.731(50)𝛥/amu. - - - 0.0096

Experimental Value

Aʹ/MHz 4478.14(14)

Bʹ/MHz 1409.359(81)

Cʹ/MHz 1069.769(52)

/cm-1 2226.051(1)

Ground State

Excited State

Aʺ/MHz 4136.96(22)

Bʺ/MHz 1358.554(73)

Cʺ/MHz 1020.539(57)

Aʹ/MHz 4118.62(17)

Bʹ/MHz 1358.691(83)

Cʹ/MHz 1019.390(56)

/cm-1 2226.072(1)

N2O-C4D2: OBSERVED SPECTRUM

Blue shifted 2.31 cm-1 w.r.t. N2O ν1

N2O-C4H2 STRUCTURE

DFT MP2 Experiment

R(8,4)/Å 3.59 3.69 3.593(3)

(8,4,5)/° 117 109 117 (3)

(9,8,4)/° 116 97 116 (12)

5: C atom 4: C4H2 center of mass8: N2O center of mass9: O atom

54

89

OBSERVATION OF CS2-C2D2 COMPLEXES

(1988). D. Prichard et al. vibration-rotation spectrum

(1989). J. Muenter et al. microwave analysis study

(1989). Z. Huang et al. near-infrared experimental study

CS2-C2D2 : SIMILAR STRUCTURES

• b-type band• Symmetric structure with C2v symmetry

Theoretical Structure Experimental structure

• Blue shifted 1.75 cm-1 w.r.t. C2D2 ν3

• Rotational temperature of 3 K

• Line-widths of 0.003 cm-1

• C2v symmetry b-type band

CS2-C2D2 : OBSERVED SPECTRUM

CS2-C2D2 : MOLECULAR PARAMETERS

Ground State

Excited State

Ground state

ab-initio Calculation (DFT)

ab-initio calculation( MP2)

Experimental Value

Aʺ/MHz 2924.89 2872.59 2921.72(47)

Bʺ/MHz 1841.10 2081.38 1823.86 (44)

Cʺ/MHz 1129.88 1206.90 1119.93(38)𝛥/amu. - - - 0.0071

Excited state Experimental Value

Aʹ/MHz 2921.38(41)

Bʹ/MHz 1823.17(45)

Cʹ/MHz 1120.11(39)

/cm-1 2438.165(1)

(DFT) Experiment

R(2,6) /Å 3.66 3.6702(74)

(DFT)

R(3,7) /Å 5.02

26

7

2

3

CS2-C2D2 : STRUCTURE

.

• Blue shifted 0.32 respect to C2D2 ν3

• Rotational temperature of 3 K

• Line-widths of 0.003 cm-1

• C2 symmetry a/b-type band

(CS2)2-C2D2 : OBSERVED SPECTRUM

(CS2)2-C2D2 TRIMER

Ground state

ab-initio calculation (DFT)

Experimental Value

Aʺ/MHz 1035.42 1025.41(15)

Bʺ/MHz 553.09 553.35 (19)

Cʺ/MHz 545.32 552.76(20)

Excited state Experimental Value

Aʹ/MHz 1025.7938(18)

Bʹ/MHz 552.87(22)

Cʹ/MHz 552.32(20)

/cm-1 2436.736(1)

Ground State

Excited State

(CS2)2-C2D2 : OPTIMIZED STRUCTURE

Ab-initio calculation

R(3,6) /Å 3.09

R(6,8) /Å 2.01

(6, 8, 9)/˚ 110.1

Γ(9,8,10,11)/˚ 25

Γ(8,6 ,3,4)/˚ 80.9

3

6

8

10

11

9

4

3:C2H2 center of mass6:(CS2)2 center of mass8:#1 CS2 center of mass10:#2 CS2 center of mass

c

a

b

SUMMARY AND CONCLUSION:

N2O-C4H2, CS2-C2D2 and (CS2)2 -C2D2

experimental and theoretical IR spectroscopy We studied

A (blue shifted ) band in the region of N2O ν1 + Two bands (blue shifted ) in the region of the C2D2 ν3

We observed and analyzed

N2O-C4H2 near parallel structure with Cs symmetry CS2–C2D2 planar structure with C2V symmetry (CS2)2 -C2D2 with C2 symmetry

We found

Thank You

M. Rezaei, J. Norooz Oliaee, N. Moazzen-Ahmadi, A.R.W. McKellar, J. Chem. Phys. 134 ,144306, (2011).

M. Rezaei, J. Norooz Oliaee, N. Moazzen-Ahmadi, A.R.W. McKellar, Chem. Phys. 13, 12635, (2011).

Should I mention ocs-c2h2!!! trimer

N2O–C2H2 Planar, near-parallel (O-in), Cs 3.296 h1 = 93.9 [113]h2 = 99.7

AB-INITIO CALCULATION ON CS2-C2D2 DIMER

Minimum energy structuressaddle point structures

Ab initio calculations@MP2 level

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DAQ Trigger

Jet Signal

IRDetectors

Etalon

OPO Module

PZTDriver

FunctionGenerator

Ref. Gas

Supersonic ExpansionNozzlesMultipass Cell

DAQ Card

Counter1

Counter3

Counter4

Counter2

TimerCard

Diffusion Pump

Mixture

Background

Jet TriggersValve Controller

Valve Controller

Laser Controller

Gas Supply

DAQ Trigger

Jet Signal

IRDetectorsEtalon

QCL

PZTDriver

Ref. GasFrequency

Locking Box

Supersonic ExpansionNozzlesMultipass Cell

DAQ Card

Counter1

Counter3

Counter4

Counter2

TimerCard

BoxcarAverager

Diffusion Pump

Mixture

Jet TriggersValve Controller

Valve Controller

Gas Supply

Laser Controller

FunctionGenerator