ABSTRACT
Multigas sensing is highly demanded in the fields of environmental monitoring, industrial production, and coal mine security. Three near-infrared emission wavelengths from PbSe quantum dots (QDs) were used to analyze the concentration of three gases simultaneously through direct absorption spectroscopy, including acetylene (C2H2), methane (CH4), and ammonia (NH3). The corresponding lower detection limits for the three gases were 20, 100, and 20 ppm, respectively, with an accuracy of 2%. This study demonstrates that QDs with tunable emissions have great potential for simultaneous and uninterfered multiplex gas analysis and detection due to the advantages of the easy tunability of multiplex emitting wavelengths from QDs.
ABSTRACT
We propose an efficient construction of the hierarchical equations of motion formalism of quantum dissipation on the basis of the Padé spectrum decomposition of the Bose function and the multiple brownian oscillators decomposition of the environment spectral density. The related hierarchical Liouville space algebra for quantum dissipative mechanics is outlined in relation to the evaluation of nonlinear optical response functions. With the simulated transient pump-probe spectroscopy of model exciton systems, we demonstrate the correlated system-environment coherence by the present nonperturbative and non-markovian quantum dissipation theory.
