ELECTRONIC STRUCTURE AND SPECTROSCOPY OF THE MGO2 CATION

O. YAZIDI, A. BEN HOURIA AND Z. BEN LAKHDAR, LSAMA, Universitè de Tunis El Manar, Tunis, TUNISIA

M. L. SENENT, Departamento de Astrofísica Molecular e Infrarroja, Instituto de Estructura de la Materia, C.S.I.C., Serrano 121, Madrid 28006, SPAIN

M. HOCHLAF, Université Paris-Est, Laboratoire de Modélisation et Simulation Multi Echelle, MSME FRE 3160 CNRS, 5 boulevard Descartes, 77454 Marne-la-Vallée, FRANCE

Chemical Physics, 215, 348 (2008)

MgO2+

Relevance for earth AtmospherePossible intermediate or product of reactions Type O3 + M+

Outline

StructureElectronic statesPhotodissociation of MgO2

+

MgO2+ → MgO+ + O (3P)

MgO2+ → Mg+ + O2 (X3Sg

-)MgO2

+ → Mg+ + O2 (1Dg)

Spectroscopic parameters from 3D-PES

MgO2+ minumum energy structures

Mg

O O

OMg O X4 S-

X2A2

DE = 0.77 eV

MRCI/CASSCF/cc-pV5ZActive space: 2s(O), 2p(O), 3s(Mg), 3p(MG)

2.4104 1.2102

42.6º

1.8913

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Ene

rgy

/eV

76543 RMgO /bohr

RMgO

Mg O O2.28

X 4

12

12

12

Mg+ ( 2Sg ) + O2( X 3g- )

Mg+ ( 2Sg ) + O2( a 1g)

Mg+ ( 2Sg ) + O2( b 1g+ )

R(MgO) /Bohr(ROO = 2.28)

l-MgOO+

X4 S-

CASSCF

8

6

4

2

0

Ene

rgy

/eV

10864 ROO /bohr

Mg O O4.55

+X4

12

12

12

12

22

14

24

24

22

12

22

14

14

MgO+ (X2 ) + O(3Pg)

MgO+ (2 ) + O(3Pg)

(A)

R(OO)/Bohr RMgO = 4.55 bohr

l-MgOO+

X4 S-

MRCI/CASSCF

4

3

2

1

0

Ene

rgy

/eV

180160140120100806040/degree

+Mg

O O4.55

2.28

1 2A"

2 2A"

3 2A"

1 2A'

2 2A'

3 2A'

1 4A"

X 4

1 2

1 2

1 2

(A)

bending angle

l-MgOO+

X4 S-

CASSCF

7

6

5

4

Ene

rgy

/eV

10864 RMgO /bohr

Mg

OO

3.56 RMgO42°

+

X 2A" 1 2A'

2 2A"

1 4A"

2 2A'

3 2A"

3 2A'

2 4A"

1 4A'

2 4A'

3 4A' 4 2A"

4 4A"

5 4A"

5 2A''

3 2A'

3 4A'

MgO+ ( X 2 ) + O( 3Pg )

MgO+ ( 2+ ) + O( 3Pg )

(A) MgO2+( 2A2)

CASSCFR(MgO)/Bohr RMgO = 3.56 bohr

6

4

2

0

Ene

rgy

/eV

1210864 R /bohr

Mg

O O

R

2.60

+z

y

X 2A2

1 2B2

22B2

1 2B1

2 2B1

3 2B1

1 2A1

2 2A1

2 2A2

1 4A2

1 4A1

(A)

Mg+ ( 2Sg ) + O2( X 3g- )

Mg+ ( 2Sg ) + O2( a 1g )

Mg+ ( 2Sg ) + O2( b 1g+ )

FC

1 4B1

14B2

MgO2+( 2A2)

MRCI/CASSCF

3D-PES

MRCI/CASSCF/cc-pV5Z l-MgOO (X4 S-) 22 geometries up to energies 700 cm-1 (along the MgO

st) up to energies 5000 cm-1 (along the OO st) Bend OMgO (X2A2 ) 35 geometries Up to energies 4000 cm-1

MgO2+( 2A2) l-MgOO+( 4S-)

ROO2.287

RMgO3.57 4.555

θe42.6 180

G01343.6 831.3

Ae1.113

Be0.393 0.1238

Ce0.292

a1A

0.001555

a2A

0.014606

a3A

-0.007097

a1B

0.003458 0.000523

a2B

-0.000995 -0.00171

a3B

0.002180 0.00398

a1C

0.001588

a2C

0.000357

a3C

0.002879

X~X~A

1 A2 A3 B1 B2 B3 C1 C2 C3

w1 667.7

660.8

1588.0

w2 1078.0

1071.8

46.1

w3 488.8

668.8

117.8

n1 641 1427.1

n2 1837 48.1

n3 511 126.8

MRCI Spectroscopic parameters

CASSCF (sta.met.MOLPRO)

X~X~A

1 A2 A3 B1 B2 B3 C1 C2 C3

(v1,v2,v3) Energy

(0,0,0) 0

(0,0,1) 511

(1,0,0) 641

(1,0,1) 1008

(0,0,2) 1158

(2,0,0) 1259

(1,0,2) 1494

(0,0,3) 1660

(3,0,0) 1784

(0,1,0) 1837

(2,0,1) 1882

(2,0,2) 1968

Variationally computed vibrational levels of MgO2+ ( 2A2). T

he energies are in cm-1.

accuracy 10 cm-1

Variationally computed vibrational levels of MgOO+ ( 4S-). The energies are in cm-1.

J=0 J=1

(v1,v2,v3) Energ

y

(v1,v2,v3) Energy (v1,v2,v3) Energy (v1,v2,v3) Energy

(0,0,0) 0 (0,6,1) 478 (0,1,0) 48 (0,3,3) 535

(0,2,0) 96 (0,10,0) 501 (0,3,0) 146 (0,9,1) 555

(0,0,1) 126 (0,0,4) 512 (0,1,1) 179 (0,1,4) 573

(0,4,0) 194 (0,2,3) 536 (0,5,0) 245 (0,11,0) 601

(0,2,1)) 229 (0,6,2) 546 (0,3,1) 282 (0,5,2) 606

(0,0,2) 256 (0,8,1) 590 (0,1,2) 314 (0,3,4) 647

(0,6,0) 295 (0,10,1) 607 (0,7,0) 347 (0,11,1) 661

(0,2,2) 333 (0,2,4) 630 (0,3,2) 387 (0,1,5) 690

(0,4,1) 367 (0,12,0) 654 (0,1,3) 424 (0,13,0) 710

(0,0,3) 392 (0,0,5) 663 (0,7,1) 450

(0,8,0) 397 (0,4,3) 689 (0,5,1) 456

(0,4,2) 439 (0,8,2) 703 (0,9,0) 493

In this work:

The atmospherically relevant MgO2+ species has been characterized.

From the Potential Energy Surfaces for various electronic states, we suggest severalphotodissociation channels.

The spectroscopic parameters of the two stable forms are determined variationnally from 3D-PES.

Summary