Cs+ depth profiling of Si at high incidence angles introduces additional transient effects and significantly longer transient widths (up to 30 nm in depth). Analysis of a well-defined delta layered Si structure with a 250 eV Cs+ ion beam incident at 75degrees, reveals that the enhancement of these transient effects are accompanied by: (a) a sputter rate reduction, (b) ripple topography formation and (c) a continually increasing implanted Cs concentration over the first similar to30 nm. Steady state sputtering ensues after this depth with no further roughening. These trends indicate that that the enhanced transient effects are initiated through surface roughening, which reduces sputter rates. A reduction in the sputter rate allows for more Cs to be retained within the near surface region, which in turn enhances negative secondary ion yields. (C) 2002 Elsevier Science B.V. All rights reserved.