Electron impact transfer rates between metastable and resonant states of argon investigated by laser pump-probe technique

The laser pump-probe technique is used to study the electron impact transfer between the 1s₅ and 1s₄ states of argon (in Paschen's notation) belonging to the ²P_3/2 ion core for electron temperatures in the range of 1-2 eV. A rate coefficient of m³s^-1 is determined for the transfer from 1s₅ to 1s₄ state. Different pumping schemes between the 1s and 2p states but also 3p states are used to verify the obtained value but also to probe the transfers with ion-core change toward the ²P_1/2 ion-core. Our results show the presence of an important transfer channel between 1s₂ and 1s₄ states, and a rate coefficient of m³ s^-1 is estimated for this transfer. The present results confirm that recent quantum mechanical calculations by Zatsarinny et al [1] underestimate significantly the cross sections for electron impact transfers between 1s states of argon.