Sterling Financial Corp. on Tuesday reported second-quarter earnings off substantially from 2007 but an improvement on first-quarter numbers. In a report issued after markets closed, the Spokane-based bank said it earned $11.7 million, or 23 cents per share, for the three months ended June 30, compared with $27 million, or 52 cents per share, for the 2007 period. During the 2008 first quarter, earnings had slumped to $2.9 million, just 6 cents per share.