Cross sections for Scattering and Mobility of OH$^{\mathrm{-}}$ and H$_{\mathrm{3}}$O$^{\mathrm{+}}$ ions in H$_{\mathrm{2}}$O*

Modelling of plasmas in liquids and in biological and medical applications requires data for scattering of all charged and energetic particles in water vapour. We present swarm parameters for OH$^{\mathrm{-}}$ and H$_{\mathrm{3}}$O$^{\mathrm{+}}$, as representatives of principal negative and positive ions at low pressures in an attempt to provide the data that are not yet available. We applied Denpoh-Nanbu procedure to calculate cross section sets for collisions of OH$^{\mathrm{-}}$ and H$_{\mathrm{3}}$O$^{\mathrm{+}}$ ions with H$_{\mathrm{2}}$O molecule. Swarm parameters for OH$^{\mathrm{-}}$ and H$_{\mathrm{3}}$O$^{\mathrm{+}}$ ions in H$_{\mathrm{2}}$O are calculated by using a well tested Monte Carlo code for a range of $E/N(E$-electric field, $N$-gas density) at temperature $T=$295~K, in the low pressure limit. Non-conservative processes were shown to strongly influence the transport properties even for OH$^{\mathrm{-}}$ ions above the average energy of 0.2~eV($E/N$\textgreater 200~Td). The data are valid for low pressure water vapour or small amounts in mixtures. They will provide a basis for calculating properties of ion-water molecule clusters that are most commonly found at higher pressures and for modelling of discharges in liquids.