Abstract: In accordance with the present invention, a multi-wavelength cross-correlator for two radiation pulses is disclosed. In one embodiment, a method for operating the cross-correlator is disclosed. A first radiation pulse is focused upon the photodiode. A second radiation pulse is also focused on the photodiode where the first and second radiation pulses illuminate a common point on the photodiode. The first and second radiation pulses, which have different wavelengths, are converted into a photocurrent using the photodiode where the product of the first and second intensities is proportional to the photocurrent. An amplitude of the photocurrent is detected while varying the delay of at least one of the first and second radiation pulses. In another embodiment, a multi-wavelength cross-correlator includes a radiation detector and a current detector. The radiation detector converts energy from the first and second radiation pulses, which have different wavelengths, into a current.

Abstract: The present invention provides a source of Group V and VI atoms, and in particular arsenic atoms, usable in MBE as a growth source or a doping source. The arsenic atoms are produced in two steps. In the first step, a sublimator vaporizes solid arsenic, producing a molecular beam of arsenic tetramers and/or dimers. The molecular beam source can optionally include a cracker to produce As.sub.2 from As.sub.4. In the second step, the molecular beam impinges on a surface of a heated element, termed an atomizer, producing an output beam containing atomic arsenic. The atomizer is at a temperature above about 1200K and a pressure below about 10.sup.-3 torr or at a temperature above about 1400K and a pressure below about 10.sup.-2 torr. For other Group V and VI elements, different atomizer temperatures and pressures are used.

Abstract: The present invention provides a photoionization mass spectroscopy flux monitor for gaseous species above a sample surface. It provides an in situ, real time, species specific, nonintrusive probe with a geometry compatible with conventional MBE growth chambers. Gaseous species are photoionized above a sample surface and the ionized gaseous species are extracted parallel to the sample surface and coupled into a mass spectrometer inlet adjacent to the sample surface. The geometry of the flux monitor allows for simultaneous coupling of a charged particle beam with the sample surface, for example for monitoring film growth with RHEED.

Abstract: Lasing can be achieved by pumping a laser cell containing a vapor formed predominantly of Group VI dimers such as S.sub.2, Te.sub.2, Se.sub.2, TeO, TeSe, TeS and SeS, from a ground electronic state to a selected vibrational-rotational level in a selected excited electronic state. The selected excited electronic state is one having allowed transitions relative to the ground electronic state and the selected level of the excited state is one that is below the dissociation limit of that state. Lasing transitions then occur between the selected excited state level and higher vibrational-rotational levels of the ground state. For example, lasing is achieved at S.sub.2 (B-X) and at Te.sub.2 (A-X).