A new set of photodissociation experiments and simulations of HI on  Ar_n 
clusters with an average size n=139
has been carried out for different laser polarizations.
The doped clusters are prepared by a pick-up process. 
The hydrogen halide molecule is then photodissociated by a
 UV laser pulse and the outgoing H fragment is ionized by resonance 
 enhanced multi-photon ionization
 (REMPI) in a (2+1)excitation scheme within the same laser pulse at a 
 wavelength of 243 nm. 
 The measured time-of-flight spectra are transformed 
into hydrogen kinetic energy distributions. 
They exhibit a strong fraction of caged H atoms at zero kinetic energy 
and peaks at the unperturbed cage exit for both spin-orbit channels 
nearly independent of the polarization. 
At this dissociation wavelength the bare HI molecule exhibits a strict 
state separation, with a parallel transition to the 
spin orbit excited state and  perpendicular transitions to the ground 
state.
The experimental results have been reproduced using molecular simulation
techniques.  
Classical molecular dynamics was used to estimate the HI dopant 
distribution after the pick-up procedure. 
Subsequently, quasi-classical molecular dynamics 
(Wigner trajectories approach) has been applied for 
the photodissociation dynamics. 
The following main results have been obtained.
(i) The HI dopant lands on the surface of the argon cluster during 
the pick-up process, (ii) zero point energy plays a dominant role for 
the hydrogen orientation in the ground state of HI-Ar$_n$ surface 
clusters, qualitatively changing the result of the photodissociation 
experiment upon increasing the number of argon atoms, and, finally, 
(iii) the scattering of hydrogen atoms from the cage which originate 
from different dissociation states seriously affects the experimentally 
measured kinetic energy distributions.