method to halt the search.
In order to get meaningful results from an asynchronous search, use the AdvancedSearchComplete event to notify you when the search has finished.
expression.IsSearchSynchronous(LookInFolders)
expression Required. An expression that returns an Application object.
LookInFolders Required String. The path name of the folders that the search will search through. It is recommended that the folder name is enclosed within single quotes.