We report deep Sub-Millimeter Array observations of 26 pre-main-sequence ( PMS ) stars with evolved inner disks .
These observations measure the mass of the outer disk ( r \sim 20-100 AU ) across every stage of the dissipation of the inner disk ( r < 10 AU ) as determined by the IR spectral energy distributions ( SEDs ) .
We find that only targets with high mid-IR excesses are detected and have disk masses in the 1-5 M _ { Jup } range , while most of our objects remain undetected to sensitivity levels of M _ { DISK } \sim 0.2-1.5 M _ { Jup } .
To put these results in a more general context , we collected publicly available data to construct the optical to millimeter wavelength SEDs of over 120 additional PMS stars .
We find that the near-IR and mid-IR emission remain optically thick in objects whose disk masses span 2 orders of magnitude ( \sim 0.5-50 M _ { Jup } ) .
Taken together , these results imply that , in general , inner disks start to dissipate only after the outer disk has been significantly depleted of mass . This provides strong support for photoevaporation being one of the dominant processes driving disk evolution .