Molecular Beam Electric resonance without A and B Fields

C. MONTERO; A. GONZALEZ UREÑA; JORGE O. CACERES; M. MORATO; JUAN J. NAJERA; H.J. LOESCH

EUROPEAN PHYSICAL JOURNAL D

SPRINGER

Lugar: Berlin; Año: 2003 vol. 26 p. 261 - 264

1434-6060

We report on a novel phenomenon observed during the passage of a pulsed NO beam seeded in He through a combined homogeneous, static electric and RF field, denoted as C-field in a standard molecular beam electric resonance (MBER) experiment. Although we refrain from the state selective A- and B-fields, which are considered crucial for a MBER experiment, the transmitted intensity exhibits as a function of the RF frequency conspicuous dips at resonance frequencies that depend strictly linearly on the static field strength E0. Their spectral width is by a factor of 4 smaller than the time of flight broadening. Both, the resonance frequencies and their linear field dependence can be precisely predicted applying a simple expression for the Stark effect to a ΔM = ±1 transition of a single rotational state (J = 3/2) of the electronic ground state 2Π1/2. However, this formula is valid only in the high field limit (E0 > 1000 kV/m) while the employed field (E0 = 1.47 kV/m) was in the extreme low field domain where the large Λ type doubling and hyperfine coupling lead to a purely quadratic Stark effect. We assume that the phenomenon is due to a yet unknown collective rather than to an isolated particle process.