NIST intends to negotiate a sole-source, urgent replacement of a non-functional Cesium Source Head for its time-of-flight secondary ion mass spectrometry (ToF-SIMS) instrument with ION-TOF USA, Inc. of Chestnut Ridge, New York. Market research and ION-TOF’s written statement indicate that ION-TOF is the only authorized and capable provider of service and spare parts for IONTOF surface analysis equipment, including TOF-SIMS IV instruments. The applicable NAICS code is 334516 (Analytical Laboratory Instrument Manufacturing), with a 1,000-employee small-business size standard. No solicitation package will be issued, but interested parties who believe they can fulfill the requirement may submit responses for Government consideration.