Photodissociation dynamics of the singlet and triplet states of the NCN radical
- Department of Chemistry, University of California, Berkeley, California 94720 (United States) Chemical Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720 (United States)
The spectroscopy and photodissociation dynamics of the NCN radical have been investigated by fast beam photofragment translational spectroscopy. The [tilde B] hthinsp;[sup 3][Sigma][sub u][sup [minus]][l arrow][tilde X] hthinsp;[sup 3][Sigma][sub g][sup [minus]], [tilde c] hthinsp;[sup 1][Pi][sub u][l arrow][tilde a] hthinsp;[sup 1][Delta][sub g], and [tilde d] hthinsp;[sup 1][Delta][sub u][l arrow][tilde a] hthinsp;[sup 1][Delta][sub g] transitions were examined. The major dissociation products for the [tilde B] hthinsp;[sup 3][Sigma][sub u][sup [minus]] and [tilde c] hthinsp;[sup 1][Pi][sub u] states are N[sub 2]([tilde X] hthinsp;[sup 1][Sigma][sub g][sup +])+C([sup 3]P), while the [tilde d] hthinsp;[sup 1][Delta][sub u] state dissociates to N[sub 2]([tilde X] hthinsp;[sup 1][Sigma][sub g][sup +])+C([sup 1]D). The dissociation channel, N([sup 4]S)+CN([tilde X] hthinsp;[sup 2][Sigma][sup +]) is observed for the [tilde B] hthinsp;[sup 3][Sigma][sub u][sup [minus]] state at photon energies greater than 4.9 eV, where it comprises [approx]25[plus minus]10[percent] of the total signal. At all photon energies, the photofragment translational energy distributions show a resolved progression corresponding to the vibrational excitation of the N[sub 2] photofragment. The rotational distributions of the molecular fragments suggest that the dissociation pathway for the N[sub 2] loss channel involves a bent transition state while the N+CN photofragments are produced via a linear dissociation mechanism. The P(E[sub T]) distributions provide bond dissociation energies of 2.54[plus minus]0.030 and 4.56[plus minus]0.040 hthinsp;eV for the N[sub 2] and CN loss channels, respectively, yielding [Delta]H[sub f,0 K](NCN)=4.83[plus minus]0.030 eV. [copyright] [ital 1999 American Institute of Physics.]
- OSTI ID:
- 6173005
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Vol. 111:11; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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