11. Diatomic Molecular Ions

The normal electronic configurations and asymptotic parameters of valence electron wavefunctions in diatomic molecular ions are presented. Numerical data are compiled for spectroscopic constants, dissociation energies and radiative lifetimes of electronically excited diatomic molecular ions and, also, for the electron affinity of diatomic molecules and the proton affinity of atoms.

11.1 Electron Configurations and Asymptotic Parameters of Wavefunctions for Valence Electrons in Diatomic Molecular Ions

Table 11.1 provides information about the ground-state electron configura­tions of some diatomic molecular ions (see Sect. 10.1 for the details of state designations, etc.). The dissociation products of the molecular ions and their related atomic states are also indicated in a separate column.

The numerical values of asymptotic coefficients of wavefunctions for val­ence electrons in some negative diatomic molecular ions are presented in Table 11.2 (Sect. 10.2 gives details of wavefunction asymptotic expansions). The parameters A (8) and y characterize the one-electron distribution (val­ence orbital) in the range where the distance r from the centre of the molecu­lar ion is large compared to the mean size of the ions themselves.

Most of the values have been rounded off to give uncertainties of a few units in the last place. The data mentioned above are based on [10.1.1-3, 10.2.1-3].

A. A. Radzig et al., Reference Data on Atoms, Molecules, and Ions© Springer-Verlag Berlin Heidelberg 1985

11.2 Spectroscopic Constants of Diatomic Molecular Ions 395

Table 11.1. Electronic configurations and terms of diatomic molecular ions

Molecule Electronic MO configuration Dissociation term products and

their states

C2 2,l'; (ag ls)2 (au ls)2 (ag2s)2 (au 2s)2 (.nu 2p)4 (ag2p) Cep) + C-eS) CO+ X2,l'+ la22a23a24a21.n45a C+ep) + Oep)

Hi X2,l'; lsag HeS) + W HeH+ X l,l' + (la)2 HeeS) + W Nt X2,l'; la~ la~2a~2~ 1.n!3ag NCSO) + Wep) NO+ Xl,l'+ (lsa)2 (2sa)2 (2pa)2 (2p.n)4 (3sa)2 (3pa)2 N CSO) + 0+ CS) NO- x 3r (lsa)2 (2sa)2 (2pa)2 (2p.n)4 (3sa)2 (3pa)2 (3p.n)2 N(4S0) + O-ep)

ot X 2IIg,j 1~ 1~2~2a~3~ 1.n! l.ng Oep) + O+CS)

02" X 2IIl12,g 1a~ 1a~2a~2~3~ 1.n! 1.n~ Oep) + O-ep) OH+ X 3,l'- la22a2 3a21.n2 0+ (4S) + HeS)

Table 11.2. Asymptotic parameters of valence electron wavefunctions for diatomic negative ions

Molecule and Valence Asymptotic parameters [a.u.] ground-state molecular term orbital y Re a b c a f3

C2(x2IIu)a l.nu 0.510 2.392 0.7 2.0 0.8 0 0 02" (X2IIg)a l.ng 0.180 2.56 1.5 2.5 0.4 1 1 OW (Xl,l'+)b 1.n 0.365 4.879 0.8 0.3 NW(X2IIj)b 1.n 0.167 1.151 0.3 0.1 CW(X3r)b 1.n 0.233 0.953 0.6 0.2

a A (9) = ach(byRecos9)(1 + ccos29) sina9cosil9 b A (9) = [1 + bexp(yRecos9)]sin9

11.2 Spectroscopic Constants of Diatomic Molecular Ions

Table 11.3 presents spectroscopic constants of diatomic molecular ions. It includes mainly the numerical data for well-known low-lying electronic states and neglects questionable values. The information contained in each column of this table was briefly commented on in Sect. 10.3. We assume that the numerical values are accurate to one or two units in the last significant figure given. The data listed are based on [10.3.1-6].

Tab

le 1

1.3.

Spe

ctro

scop

ic c

onst

ants

of

diat

omic

mol

ecul

ar i

ons

IH

\C

0\

Ion

Ele

ctro

nic

Ter

m e

nerg

y E

quili

briu

m

Vib

ratio

nal

Anh

arm

onic

Rot

atio

nal

Rot

atio

n-Fo

rce

con-

Obs

erva

ble

Red

uced

te

rm

To [

cm-l

] in

tern

ucle

ar

freq

uenc

y co

nsta

nt

cons

tant

vi

brat

ion

stan

t k

e el

ectr

onic

m

ass

dist

ance

W

e [c

m-l

] w.

,xe [

cm-l

] B

e [

em-l

] in

tera

ctio

n [1

05 d

ynlc

m]

tran

siti

on

fJ-A

[a.m

.u.]

.....

~

T.

[A]

cons

tant

ae

~ [1

0-3

cm-l

] 0

1 2

3 4

5 6

7 8

9 10

11

~. s::

AlH

+ X

2 J;+

0 1.

602

.... 1

620

6.76

40

0 1.

5 0.

972

~ A

rH+

XlJ

;+

0 1.

28

2589

.28·

61

10

.46

375

4.26

0.

983

e. A

sO+

AlJ

I 42

594.

2 1.

69

780.

8 7.

4 0.

449

4.7

4.73

A

-+X

!!l -

XlJ

;+

0 1.

57

1091

.3·

5.0

0.52

0 3.

1 9.

4 13

.18

0 1:1 '"

AsS

+ A

lJI

3735

9.7

2.08

44

1.2

3.4

0.17

3 1.

2 2.

57

A-+

X

XlJ

;+

0 1.

945

644.

2 2.

1 0.

199

0.9

5.49

22

.45

BeH

+ A

lJ;+

39

417.

0 1.

609

1476

.1

14.8

7.

184

125

1.16

A

-+X

X

lJ;+

0

1.31

2 22

21.7

39

.8

10.8

0 29

4 2.

64

0.90

7

C2

B2J;

: 18

390.

88

1.22

3 19

68.7

14

.43

1.87

7 17

.8

13.7

B

_X

X2

J;;

0 1.

2682

17

81.0

11

.58

1.74

7 16

.7

11.2

6.

006

CH

+ Bl

Ll

5253

0 1.

232

2075

.5

76.3

11

.94

620

2.36

B

-+A

b3

J;-

3820

0 1.

245

1940

· 11

.71

540

b-+

a A

lJI

2359

6.9·

1.

234

1865

.3

115.

8 11

.90

941

1.91

A

_X

a3

JI

.... 9

200

1.13

6 28

10

14.0

5 60

3 4.

3 Xl

J;+

0 1.

131

2739

.7"

64

14.1

78

492

4.5

0.93

0 C

N+

pJ;

x +

455

33.6

1.

171

2670

.5

47

1.90

3 32

27

.2

f-+

b, a

cl

J;

x +

317

70

1.36

12

65

11

1.40

2

6.10

c-

+ a

bl

JI

x +

831

3.6

1.24

7 16

88.3

15

.1

1.67

7 19

.1

10.9

al

J;

x 1.

173

2033

.0

16.1

1.

896

18.8

15

.8

6.47

C

O+

C2 L

lr 63

012

1.35

11

44

33.3

1.

357

24

5.29

C

-+A

B

2 J;+

4587

6.7

1.16

9 17

34.2

27

.9

1.80

0 30

.3

12.2

B

_X

,B-+

A

-A

2 JI i

2073

3.3

1.24

4 15

62.1

13

.5

1.58

9 19

.4

9.86

A

-+X

X

2 J;+

0 1.

115

2214

.2

15.2

1.

977

19.0

19

.8

6.86

06

CS+

A 2

lli

1199

0 1.

641

1013

6.

5 0.

718

6.2

5.28

A~X

X2~+

0 1.

495*

13

8 0.

864*

9.

9 8.

738

CdH

+

A l~+

4293

4.1

1.86

5 12

52

8.6

4.85

82

0.

92

A~X

Xl~+

0 1.

667

1772

.5

35.4

6.

07

190

1.85

0.

999

Cli

X

/ll 1

/2g

645

1.89

1 64

4.8

2.99

0.

2697

1.

67

4.34

X1

2ll3

/29

0 1.

892

645.

6 3.

02

0.26

95

1.64

4.

35

17.7

3

Pi

X2 l

l g,i

0 1.

32

1073

9.

1 1.

01

10

6.45

9.

50

Hi

X2

I;(l

sa)

0 1.

05

2322

66

30

.2

1680

1.

60

0.50

4 H

Br+

A

2I+

28

421

1.68

4 14

04

37.7

5.

970

248

1.16

A~X

......

X2 l

li

0 1.

448

2441

.5

47.4

8.

072

236

3.50

0.

995

......

N

HC

l+

A2I

+

2862

6 1.

514

1606

.5

40.3

7.

505

331

2.90

A~X

v.>

X2 l

li

0 1.

3147

26

73.7

52

.54

9.95

66

327

8.02

1.

904

'1:1 0

HF

+

A2I

+

2544

9.8

1.22

4 14

96.1

88

.4

11.7

5 10

26

1.26

A~X

~ 8

X2 l

li

0 1.

001

3090

.5

89.0

17

.58

886

5.39

0.

957

en 8

Hei

X

2 I:

0 1.

081

1698

35

7.

21

224

3.40

2.

001

~.

HeH

+

XII

+

0 0.

774

3228

15

8 34

.9

2640

4.

94

0.80

5 (J

HgA

r+

X2 I

+

0 2.

87*

99

1.5

0.06

1'

0.2

33.3

1 0 ::s en

H

gH+

A

II+

44

317

1.69

3 16

24

45.1

5.

87

200

1.56

A~X

S"

XII

+

0 1.

594

2028

41

6.

61

206

2.43

1.

003

a L

'+

X2

I;

0 3.

1 26

0 1.

6 0.

496

5 0.

14

3.47

0 0

12

....,

MgH

+

Bil

l 50

480

2.27

" 5

27

' 3

.38

' 28

0 B~X

tJ

AII

+

3590

4.5

2.00

6 11

36

8.18

4.

330

68

0.74

A~X

~.

XII

+

0 1.

652

1699

31

.9

6.38

7 18

2 1.

65

0.96

8 ~.

N

i C

2 I:

6460

9 1.

263

2069

8

1.51

0 -1

17

.7

C~X

~

D2ll~,i

5231

8 1.

471

907.

7 11

.9

1.11

3 20

3.

40

D~A

0 (b

B2I

u 25

461.

1 1.

075

2421

24

.1

2.08

5 21

24

.2

B_

X

E. A

2ll

u,i

9167

.5

1.17

5 19

03.4

6 15

.02

1.74

44

18.9

15

.0

A~X

'" .... X

2I;

0

1.11

64

2207

.27

16.2

6 1.

9318

19

.0

20.1

7.

003

-0 ::s N

H+

C

2 I+

35

000

1.16

3 21

50.5

73

.1

13.2

6 79

0 2.

56

C~X

en

A2 I

-22

200

1.25

1 17

07

61

11.4

6 69

0 1.

6 A~X

X2 l

lr

0 1.

07

2922

' 1

5.3

' 64

0 0.

940

w

\D

--l

Tab

le 1

1.3

(con

tinu

ed)

..., \0

00

Ion

Ele

ctro

nic

Ter

m e

nerg

y E

quili

briu

m

Vib

ratio

nal

Anh

arm

onic

Rot

atio

nal

Rot

atio

n-F

orce

con

-O

bser

vabl

e R

educ

ed

term

To

[cm

-I]

inte

rnuc

lear

fr

eque

ncy

cons

tant

co

nsta

nt

vibr

atio

n st

ant

ke

elec

tron

ic

mas

s di

stan

ce

We

[cm

-I]

WeX

e [c

m-I

] Be

[cm

-I]

inte

ract

ion

[105

dyn

/cm

] tr

ansi

tion

f-l

A [a

.m.u

.]

>-'

:--

re [

A]

cons

tant

ae

t::!

[10-

3 cm

-I]

~.

1 2

3 4

5 6

7 8

9 10

11

2. n ~

NO

+ A

lII

7347

1.8

1.19

4 16

01.9

20

.2

1.58

4 22

11

.3

A~X

~

WIL

l 71

650

1.30

12

20

12

1.33

17

6.

52

E-A

/1l'

-69

540

1.29

12

80

13.2

1.

36

18

7.21

~ .... .....

b,3 I

-67

780

1.28

12

83

11

1.39

25

7.

25

b/~X

0 ::s w

3 L1

6191

0 1.

28

1320

11

1.

38

16

7.63

'"

b3 I

I 59

180

1.17

6 17

10

14.2

1.

634

18.4

13

b~X

a3 I

+

5215

0 1.

28

1300

15

1.

37

20

7.47

X

1l'+

0

1.06

3 23

76.7

16

.3

1.99

7 18

.8

24.8

6 7.

468

NO

-X

3 l'-

EA

(NO

) =24

0 1.

26

1360

8

1.43

8.

2 7.

468

NS+

X

Il'+

0

1.44

14

10

15

0.83

10

11

.5

9.74

8

ot

c4 I

';

1009

10

1.16

" 15

45"

1.56

" c~ b

b4

I~

4955

0 1.

280

1196

.8

17.1

1.

287

22.1

6.

75

b~a

A2I

Iu

4066

9 1.

409

898.

2 13

.6

1.06

2 19

.4

3.80

A~X

a4 I

Iu,i

3296

0 1.

381

1035

.7

10.4

1.

105

15.8

5.

06

X2I

Ig

{ ~9

7.3

1.11

6 19

04.8

16

.3

1.69

1 19

.8

17.1

8.

000

Oz-X

2 II

{3/2

16

0 1.

35

1090

8

1.16

5.

6 8.

000

g,i

112

0 O

H+

blI

+

2905

0 1.

03

2980

· 16

.32"

73

0 A

3II

i (1)

28

439

1.13

5 21

33.6

79

.5

13.7

92

890

2.54

A~X

X3 I

-0

1.02

9 31

13.4

78

.5

16.7

94

750

5.41

0.

948

OW

X

II+

0

0.96

4 37

00

19.1

3 77

0 7.

6 0.

948

Pi

C22

n f/

2

2887

1 2.

243

441.

5 2.

6 0.

2163

1.

4 1.

78

C2~XI

CI

9 11

2 28

687

CI~X2

B22;

+

2557

0 2.

12

410.

5 3.

2 0.

242

2.1

1.54

B~A

D2

2;

{112

18

832

2.23

46

2 2.

4 0.

220

1.4

1.95

D2~X2

DI

9 3/

2 18

741

DI~XI

A 2

2;;

2180

1.

89

733"

0.

304

2

X22

n {1

12

260

1.98

6 67

2.2

2.7

0.27

60

1.5

4.12

15

.49

XI

u 3/

2 0

PF+

A 2

2;

3543

5 1.

600

619.

0 4.

6 0.

559

8 2.

66

A~X

X2 I

I,

0 1.

500

1053

.2

5.1

0.63

6 5

7.70

11

.78

.....

PH+

A 2

L1,

2622

0 1.

549

1535

69

7.

196

422

1.35

A~X

.....

N

X2 I

I,

0 1.

425

2382

.7

41.7

8.

509

244

3.27

0.

976

til '"

SH+

A 3

IIi

2991

2'

1.52

" 7.

475'

A~X

('J) n

X3 2

;-0

1.37

4'

2560

50

9.

134"

28

0 3.

8 0.

977

8 '" SO

+ A

2IIi

31

422.

7 1.

657

805.

4 6.

3 0.

5759

5.

8 4.

07

A~X

8 '" X

2 II,

{

~40

1.42

4 13

07.1

7.

74

0.78

00

6.3

10.7

10

.67

n'

n 0

SiH

+ A

lII

390.

2'

70

4.91

2 76

7 0.

16

A~X

:l

2584

6 1.

878

:4

X 1

2; +

0

1.50

4 21

57.2

34

.2

7.66

0 21

0 2.

67

0.97

3 '" :l !;

r Zn

H+

A 1

2;+

4670

0 1.

72

1360

15

5.

77

105

1.09

A~X

0 X

I2;+

0

1.51

19

20

40

.... 7.

41

240

2.15

0.

993

0 ~. e. n is: ~ n e. '" ..., -0 :l

en

W

\0

\0

400 11. Diatomic Molecular Ions

11.3 Dissociation Energies of Diatomic Molecular Ions

Tables 11.4, 5 give the values of ground-state dissociation energies (Do) of diatomic molecular ions which correspond to the transition from the zero vibrational level to the continuum of atomic states. Dissociation energies of positive and negative molecular ions were calculated on the basis of ther­mochemical relations for the separate stages in the cycles (see also Fig. 11.1):

Do (A - B+) = Do (A - B) + IP(B) - IP(AB) ,

Do (A - B-) = Do (A - B) + EA(AB) - EA(B) ,

where IP is the ionization potential of a particle and EA the electron affinity. In selecting the data for Tables 11.4, 5 we made use of [11.3.1-4] and

some later publications. The numerical values listed are grouped into the accuracy classes defined in the Introduction.

References

11.3.1 H.M.Rosenstock, K.Draxl, B.W.Steiner, J.T.Herron: "Energetics of Gaseous Ions", J. Phys. Chem. Ref. Data 6, Suppl. 1 (1977)

11.3.2 L.V.Gurvitch, G.V.Karachevtsev, V.N.Kondratjev, Y.A.Lebedev, V.A.Medvedev, V.K.Potapov, Y.S.Hodeev: Bond Dissociation Energies, Ionization Potentials, and Electron Affinities, 2nd ed. (Nauka, Moscow 1974) (in Russian)

11.3.3 K.P.Huber, G.Herzberg: Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules (Van Nostrand Reinhold, New York 1979)

11.3.4 K.S.Krasnov (ed.): Molecular Constants for Inorganic Compounds (Chimia, Moscow 1979) (in Russian)

Table 11.4. Dissociation energies Do leV] of positive diatomic molecular ions

I) Homonuclear system: Xi

X= Ag Ar As Br C Cl Cs Do 1.9 (D) 1.23 (B) 2.7 (D) 3.26 (B) 5.3(C) 3.99 (B) 0.62 (C)

X= D F Ge H He Hg I Do 2.692 (A) 3.34 (B) 2.8 (D) 2.650 (A) 2.36 (A) 0.9 (D) 2.68 (A)

X= K Kr Li N Na Ne 0 Do 0.79 (B) 1.15 (B) 1.29 (A) 8.713 (A) 0.98 (B) 1.16 (C) 6.66 (A)

X= P Pb Rb S Sb Se Sr Do 5.0 (B) 1.7 (D) 0.75 (C) 5.4 (B) 2.7 (D) 4.4 (B) 0.77 (C)

X= Te Ti V Xe Do 3.4 (B) 1.8 (D) 2.8 (D) 1.03 (C)

11.3 Dissociation Energies of Diatomic Molecular Ions 401

Table 11.4 (continued)

II) Heteronuclear system: XY+

Ion CH+ CN+ CP+ CS+ CaCl+ CdH+ CoCl+ Do 4.08 (A) 4.9 (B) 5.2(C) 6.38 (A) 4.2(C) 2.1 (D) 3.0(D)

Ion GeBr+ GeC+ GeCl+ GeH+ GeSi+ GeTe+ HBr+ Do 4.1 (C) 2.3 (D) 4.9(C) 3.9(C) 2.8 (D) 4.2 (D) 3.89 (A)

Ion HCl+ HI+ OH+ HS+ InS+ InSe+ IrC+ Do 4.65 (A) 3.12(A) 5.1 (B) 3.5 (C) 1.7 (D) 1.3 (D) 6.1 (D)

Ion IBr+ ICl+ MgCl+ NF+ PF+ PCl+ PS+ Do 2.4 (B) 2.5 (B) 3.4 (D) 5.54 (A) 5.2 (B) 3.0 (D) 6.5 (D)

Ion PbCl+ PbS+ PbSe+ PbTe+ SiBr+ SiC+ SnBr+ Do 3.0(D) 2.4 (D) 2.0(D) 1.7 (D) 4.4 (C) 3.5 (D) 3.5(D)

Ion SnC+ SnSe+ SnTe+ SrCl+ TiS+ Do 2.4 (D) 1.7 (D) 1.6 (D) 4.2(C) 4.1 (D)

ill) Rare gas system: R-R+

He Ne AI Kr Xe

He+ 2.37 (A) 0.047 (C) 0.17 (C) 0.22 (C) 0.28 (C) Ne+ 0.69(C) U6(C) AI+ 0.06 (D) 0.08 (C) 1.23 (B) 0.59 (C) Kr+ 0.055 (C) 0.59 (C) U5(B) Xe+ 0.041 (C) 0.14 (D) 0.37 (C) 1.03 (C)

IV) Heteronuclear system: X+-O

X=Ai As B Ba Be C Ca Ce Cl Do 1.78 (B) 7.7 (C) 3.1 (D) 4.1 (C) 3.8(C) 8.34 (A) 3.9(D) 8.5 (D) 5.3 (D)

X= Co Cr Fe Ga Ge Mn N Ni 0 Do 2.8(C) 3.4 (B) 3.0(C) 0.5 (D) 4.6(C) 2.5(C) 10.85 (A) 1.9 (C) 6.66 (A)

X=P Pb Pd Pr Rh S Si Sn Sr Do 8.7 (B) 2.2 (D) 1.6 (D) 8.5 (C) 2.2 (D) 5.4 (B) 5.0(B) 2.3 (D) 4.0 (D)

X= Ta Te Th Ti U V W Zr Do 10.3 (C) 4.2(C) 8.9(C) 6.8(C) 8.1 (C) 7.7 (D) 5.6 (D) 8.0(C)

V) Heteronuclear system: X+-F

X= Br C Ca Cl Cu Dy Er Eu Ga Do 2.6(C) 8.0(C) 5.6(C) 2.9(C) 2.8 (D) 5.2(C) 5.5 (D) 5.1 (D) 1.3 (D)

X= Gd Ge H He Ho I In Kr La Do 5.9 (D) 5.6(C) 3.42 (A) 1.4 (D) 5.6 (D) 2.8 (C) 1.5 (D) 1.6 (C) 5.5 (D)

X= Mg N Ne Ni P Pb S Sc Si Do 4.6(C) 5.2(D) 1.3 (D) 4.2(C) 6.7 (D) 3.6 (D) 4.1 (C) 6.4 (C) 6.4 (C)

X = Sn Sr Y Do 4.9(C) 6.4 (C) 6.2(C)

402 11. Diatomic Molecular Ions

Table 11.4 (continued)

VI) Potential parameters of alkali diatomic molecular ions (upper line: Do - dissociation energy in eV; lower line: rm - equilibrium distance between nuclei in A)

Li Na K Rb Cs

Li+ 1.28 (A) 0.94 (C) 0.56 (D) 0.42 (D) 0.28 (D) 3.23 (B) 3.38 (B) 3.72 (B) 3.8(C) 4.0(C)

Na+ 1.0 (C) 0.61 (C) 0.49 (D) 0.36 (D) 3.43 (B) 3.9(C) 4.0(C) 4.3(C)

K+ 0.80 (C) 0.74 (C) 0.57 (D) 4.14(B) 4.3(C) 4.6(C)

Rb+ 0.74 (B) 0.60 (C) 4.52 (B) 4.6(C)

Cs+ 0.65 (C) 4.78 (B)

Table 11.5. Dissociation energies Do leV] of negative diatomic molecular ions

I) Homonuclear system: Xi"

X= Br C CI F I Li 0 S Do 1.15 (B) 8.5 (B) 1.3 (B) 1.3 (C) 1.0 (C) 0.9 (D) 4.09 (A) 3.95 (A)

IT) Heteronuclear system: XY-

lon BO- BeO- CW CN- CS- KrCI- Licr LiF-Do 9.6(C) 4.9(C) 3.43 (A) 10.3 (A) 6.3 (B) 0.13 (D) 1.8(C) 2.9(C)

Ion LiW NH- NO- NS- NaCI- OW PW PO-Do 2.0(C) 3.1 (C) 5.06 (A) 3.9(C) 1.3 (D) 4.752(A) 3.3(C) 5.8 (B)

Ion SF- SW SO- SeF- SeH- SeS- SiW XeCr Do 2.8 (D) 3.8 (B) 2.4 (C) 2.8 (D) 3.2 (D) 4.4 (D) 3.0(C) 0.32 (C)

11.4 Electron Affinities of Diatomic Molecules 403

Fig. 11.1. Schematic diagram of electronic terms for molecular species XY, XY+ and XY- showing their relative positions and ex­plaining some energy relations

11.4 Electron Affinities of Diatomic Molecules

Table 11.6 lists the values of the electron affinity (EA) of neutral diatomic molecules, characterizing the lowest energy required to remove an electron from the molecular negative ion. The numerical data on EAs were grouped into the accuracy classes defined in the Introduction. The main information about electron affinities of neutral molecules is collected in [11.4.1-7].

References

11.4.1 H.S.W.Massey: Negative Ions, 3rd ed. (Cambridge University Press, Cambridge 1976) 11.4.2 B.M.Smirnov: Negative Ions (McGraw-Hill, New York 1981) 11.4.3 B .K.Janousek, J .I.Brauman: "Electron Affinities", in Gas Phase Ion Chemistry, Vol. 2,

ed. by M.T.Bowers (Academic, New York 1979) Chap. 10, pp. 53-86 11.4.4 R.R.Corderman, W.C.Lineberger: "Negative Ion Spectroscopy", Annu. Rev. Phys.

Chern. 30, 347-378 (1979) 11.4.5 H.M.Rosenstock, K.Draxl, B.W.Steiner, J.T.Herron: "Energetics of Gaseous Ions", J.

Phys. Chern. Ref. Data 6, Suppl. 1 (1977) 11.4.6 L.V.Gurvitch, G.V.Karachevtsev, V.N.Kondratjev, Y.A.Lebedev, V.A.Medvedev,

V.K.Potapov, Y.S.Hodeev: Bond Dissociation Energies, Ionization Potentials, and Electron Affinities, 2nd ed. (Nauka, Moscow 1974) (in Russian)

11.4.7 P.S.Drzaic, J.Marks, J.I.Brauman: "Electron Photodetachment from Gas Phase Molecular Anions", in Gas Phase Ion Chemistry, Vol. 3, ed. by M.T.Bowers (Academic, New York 1984) Chap. 21, pp. 167-211

404 11. Diatomic Molecular Ions

Table 11.6. Electron affinities (EA) of diatomic molecules

Molecule EA leV] Molecule EA[eV] or radical or radical

Alz 2.42 (C) Liz 0.7 (D) AlO 3.6(C) LiCI 0.6 (D) AsBr 1.3 (C) LiP 0.44 (C) AsCI 1.3 (C) LiH 0.3 (D) AsF 1.3 (C) LiN 0.4 (D) AsH 1.0 (D) MgH 1.05 (C) BO 3.0(C) NH 0.38 (B) Bez 0.3 (D) NO 0.03 (D) BeH 0.7 (D) NS 1.19 (A) BeO 1.8(C) NaCI 0.66 (C) Brz 2.6(C) NaH 0.32 (D) Cz 3.39 (B) Oz 0.44 (B) CBr 1.7 (C) OH 1.8277 (A) CF 3.3(C) OD 1.8255 (A) CH 1.24 (A) PH 1.03 (A) CN 3.82 (A) PO 1.11 (B) CS 0.21 (C) Sz 1.66 (B) CaH 0.93 (C) SF 2.5(C) Clz 2.44 (B) SH 2.31 (A) ClO 2.0 (D) SO 1.09 (C) Fz 2.96 (B) SeH 2.21 (C) FeO 1.49 (B) SiH 1.28 (A) Iz 2.51 (B) ZnH 0.95 (D) mr 2.6(C)

11.5 Proton Affinities of Atoms

The proton affinity (PA) of an atom is defined as the energy released in the protonation reaction: A + H+ ~ AH+. The most important methods for determining the atomic PAs are the collisional ionization technique (based on the measurement of the appearance potential in mass spectrometers) and thermochemical calculations [11. 5.1] .

The numerical values of atomic PAs in Table 11.7 are grouped according to accuracy classes (see the Introduction) and here we followed the authors' estimated errors. The basic information about the proton affinity of atoms may be found in [11.5.1-4]'

References

11.5.1 L.V.Gurvitch, G.V.Karachevtsev, V.N.Kondratjev, Y.A.Lebedev, V.A.Medvedev, V.K.Potapov, Y.S.Hodeev: Bond Dissociation Energies, Ionization Potentials, and Electron Affinities, 2nd ed. (Nauka, Moscow 1974) (in Russian)

11.5.2 R.Walder, J.L.Franklin: Int. J. Mass Spectrom. Ion Phys. 36, 85 (1980) 11.5.3 D.K.Bohme, G.I.Mackay, H.I.Schiff: J. Chern. Phys. 73, 4976 (1980) 11.5.4 S.G.Lias, J.F.Liebman, R.D.Levin: J. Phys. Chern. Ref. Data 13, 695 (1984)

11.6 Lifetimes of Excited Electron States in Diatomic Molecular Ions 405

Table 11.7. Proton affinities (PA) of atoms

Atom PAleY] Atom PAleY]

Ar 3.87 (A) N 3.4 (C) Br 5.7 (B) Ne 2.08 (B) Cl 5.3(B) 0 5.1 (B) Cs 7.6(C) S 6.9(C) F 3.42 (A) Xe 5.1 (C) H 2.650 (A) Zn 6.8(C) He 1.845 (A) I 6.3 (B) Kr 4.4 (B)

11.6 Lifetimes of Excited Electron States in Diatomic Molecular Ions

Table 11.8 provides values of the radiative lifetimes of excited electron states in a number of diatomic molecular ions (see Sect. 10.7 for the details of notation and [10.7.1-7]). In the separate columns of the table one finds the symbols of excited electron states of the molecular ions and the values of the transition energy, referred to the zero vibrational levels of the upper electron state and of the ground state. The accuracy of the values of T is indicated as usual (see the Introduction).

406 11. Diatomic Molecular Ions

Table 11.S. Radiative lifetimes of electronically excited diatomic molecular ions

Ion Excited state Excitation energy Radiative lifetime (ground state) Too leV] rei (v' = 0) [I-Is]

relative to zero vibrational level of the ground state

CD+eI+) Aln 2.94 0.06 (D) CWeI+) BiLl 6.46 0.23 (D)

b 3I- 4.6 0.48 (D) Aln 2.93 0.36 (D)

CO+eI+) B2I+ 5.66 0.054 (C) A 2n i 2.53 3.8(C)

CWeI) din (a + 5.66) 0.024 (D) DBr+eni) A2I+ 3.48 3.6(C) Fien i) A 2n u,i 2.75 1.4 (v' = 6-9)( C) HBr+(~ni) A2I+ 3.46 4.4 (C) HCl+eni) A2I+ 3.48 2.6(C) NieI;) C2I: 8.00 0.06 (D)

B2I: 3.17 0.063 (B) A2n u.i 1.12 17 (C)

NWen,) C2I+ 4.285 0.4 (D) B 2Ll i 2.85 1.0 (D) A 2I- 2.67 1.1 (D)

NO+eI+) Aln 9.06 0.05 (D) Oien g) b4I~ 6.10 1.2 (C)

A2nu 4.97 0.8(D) OH+eI-) A 3n i 3.47 0.85 (C) OD+er) A 3n i 3.48 1.0 (C) SH+eE-) A 3IIi 3.71 1.1 (C)