Christina M. Rudzinski

Quantum-dot optical temperature probes

The steady-state photoluminescence (PL) properties of cadmium selenide quantum dots (QDs) with a zinc sulfide overlayer [(CdSe)ZnS] can be strongly dependent on temperature in the range from 100 to 315 K. The PL intensity from 50 to 55 A (CdSe)ZnS QDs in poly(lauryl methacrylate) matrices increases by a factor of ∼5 when the temperature is decreased from 315 to 100 K, and the peak of the emission band is blueshifted by 20 nm over the same range. The change in PL intensity is appreciable, linear, and reversible (−1.3% per °C) for temperatures close to ambient conditions. These properties of (CdSe)ZnS dots are retained in a variety of matrices including polymer and sol–gel films, and they are independent of excitation wavelength above the band gap. The significant temperature dependence of the luminescence combined with its insensitivity to oxygen quenching establishes (CdSe)ZnS dots as optical temperature indicators for temperature-sensitive coatings.

Lanthanide-ion modified cyclodextrin supramolecules

Abstract A cyclodextrin appended with a lanthanide-ion macrocycle comprises a microscopic bucket that lights up when filled with mono- and bicyclic aromatics. This triggered luminescence response arises from an absorption-energy transfer-emission (AETE) process where blue light, absorbed by the aromatic, is transferred to the lanthanide ion to produce the emitting 5 D 0 excited state of Eu 3+ or the 5 D 4 excited state of Tb 3+ ion. Three supramolecule systems are presented, focusing on the design features that lead to the best luminescence response.

Screening maritime shipping containers for weapons of mass destruction

Tens of millions of shipping containers enter U.S. seaports every year carrying commerce surpassing 1.5 trillion dollars in value. As a result, the maritime shipping industry offers an attractive channel for terrorist organizations to smuggle weapons of mass destruction into the U.S., or to cripple the U.S. economy by directly attacking major ports and maritime infrastructure. In order to prevent such an event from occurring, the Department of Homeland Security has initiated the SAFECON and TRUST programs aimed at improving security measures to detect anomalous goods such as these threats in container air. These programs are working to develop aggressive solutions that minimize any disruption to the flow of commerce by identifying or developing airsample based sensors that can be installed on port gantry cranes or housed within shipping containers themselves. This paper describes the DHS Container Security Test Bed that is being established at the Transportation Security Laboratory to enable realistic evaluation of technologies against real operational challenges. Information highlighting many of these challenges including the concentrations and movement of threat simulants inside containers, background clutter, operational environment, and air sampling capabilities will be presented. This information and the additional data that is being collected at the test bed will allow us to derive sensor and operational requirements and enable the intelligent design and selection of critical technologies.