An Analysis of the 3 band of HTO aided by the Partridge and

Schwenke PES

Modou Tine and Laurent H. Coudert

Laboratoire Inter-Universitaire des Systèmes Atmosphériques

Créteil, France

Why?

•Only the ground state1 and the 1 band2 have been studied under high-resolution.

•HTO is an unstable species found in accidental releases from nuclear reactor. Half life is 12.3 years.

1Helminger et al., Phys. Rev. A 10, 1072 (1974)2Cope et al., J. Molec. Spectrosc. 127, 464 (1988)

Overview

2. The experimental spectrum of the 3 band.

1. The vibrational modes and vibrational states.

3. The first analysis of the 3 band.

4. Energy level calculation with Partridge and Schwenkee’s PES1

1Partridge and Schwenkee, JCP 106, 4618 (1997)

5. Taking into account the perturbation.

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The infrared spectrum

It was recorded in 1972 by Guy Steenbeckeliers and Andre Fayt at Louvain University in Belgium. They used an Ebert-Fastie grating spectrometer with a 0.035 cm1 resolution.

The HTO sample cell

A 7 inch long cell was

filled with a mixture of

T2O and H2O.

The experimental spectrum

322321523524

a- and b-type transitions

The first analysis

It was carried out using a Watson-type Hamiltonian for the

ground and (001) vibrational states. Rotational and

distortion constants in the ground state were set to the

values of Helminger et al.1

1Helminger et al., Phys. Rev. A 10, 1072 (1974)

First analysis: The obs. cal. table

48 lines were excluded because there is a perturbation.

533 lines were assigned. The RMS deviation is 0.018 cm1

The effects of the perturbation

8 levels of the (001) state are very perturbed.

Using the Partridge and Schwenke PES

We can obtainvibrational states

Accounting for the perturbation

The data for the (001) state and the calculated energylevels for the (110) state will be fit together.

Final analysis: The obs. cal. table

520 transitions fitted. The RMS deviation is 0.014 cm1

Only 13 transitions were excluded.

Final analysis: The perturbed levels

RMS deviation for the (110) state is 0.16 cm1

Final analysis: The constants in cm1