CCL: Seeing molecular orbitals?

Dear CCL:
 In a recent, most interesting publication ('Seeing molecular orbitals',
 Chem.Phys.Letters 321, 78-82 [2000]) scanning tunneling microscopy is used to
 observe the shapes of single molecular orbitals of the fullerene C60:
   "..the scanning tunneling microscope (STM) is probing a single molecular
   orbital (MO)."
 However, this reminds me of previous statements in the literature some time
 ago, associated with the advent of molecular photoelectron spectroscopy, f.i.
   "Chemists can see the orbital structure of even fairly large molecules
 and no
   longer have to rely on the predictions of theoreticians"
   "Photoelectron spectroscopy has demonstrated experimentally to chemists,
   physicists and other sceptics that molecular orbitals really do exist"
 I wonder whether this is acceptable terminology, considering the fact
 that molecular orbitals are model constructs; they are not physical
 observables. By using approximations, such as Koopmans' approximation, many
 experimental observations can be conveniently interpreted in terms of
 theoretical MO data. But strictly speaking, this does not turn MOs into
 observable quantities; MOs have no physical existence.
 Any comments?
 Yours, Jens >--<
 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 JENS SPANGET-LARSEN         Phone:  +45 4674 2000  (RUC)
 Department of Chemistry             +45 4674 2710  (direct)
 Roskilde University (RUC)   Fax:    +45 4674 3011
 P.O.Box 260                 E-Mail: JSL ( ( at ) ) virgil.ruc.dk
 DK-4000 Roskilde, Denmark   http://www.rub.ruc.dk/dis/chem/psos/
 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=