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Abstract The proliferation of Internet-of-Things has promoted a wide variety of emerging applications that require compact, lightweight, and low-cost optical spectrometers. While substantial progresses have been made in the miniaturization of spectrometers, most of them are with a major focus on the technical side but tend to feature a lower technology readiness level for manufacturability. More importantly, in spite of the advancement in miniaturized spectrometers, their performance and the metrics of real-life applications have seldomly been connected but are highly important. This review paper shows the market trend for chip-scale spectrometers and analyzes the key metrics that are required to adopt miniaturized spectrometers in real-life applications. Recent progress addressing the challenges of miniaturization of spectrometers is summarized, paying a special attention to the CMOS-compatible fabrication platform that shows a clear pathway to massive production. Insights for ways forward are also presented. 

Binuclear alkyne manganese carbonyls of the type (RC≡CR')Mn₂(CO)_n(R and R'=methyl or dimethylamino;n=8, 7, 6) and their isomers related to the experimentally known (MeC₂NEt₂)Mn₂(CO)_n(n=8, 7) structures have been investigated by density functional theory. The alkyne ligand remains intact in the only low energy (Me₂N)₂C₂Mn₂(CO)₈isomer, which has a central Mn₂C₂tetrahedrane unit and is otherwise analogous to the well‐known (alkyne)Co₂(CO)₆derivatives except for one more CO group per metal atom. The low‐energy structures of the unsaturated (Me₂N)₂C₂Mn₂(CO)_n(n=7, 6) systems include isomers in which the nitrogen atom of one of the dimethylamino groups as well as the C≡C triple bond of the alkyne is coordinated to the central Mn₂unit. In other low‐energy (Me₂N)₂C₂Mn₂(CO)_n(n=7, 6) isomers the alkyne C≡C triple bond has broken completely to form two separate bridging dimethylaminocarbyne Me₂NC ligands analogous to the experimentally known iron carbonyl complex (Et₂NC)₂Fe₂(CO)₆. The (alkyne)Mn₂(CO)_n(n=8, 7, 6) systems of the alkynes MeC≡CMe and Me₂NC≡CMe with methyl substituents have significantly more complicated potential surfaces. In these systems the lowest energy isomers have bridging ligands derived from the alkyne in which one or two hydrogen atoms have migrated from a methyl group to one or both of the alkyne carbon atoms. These bridging ligands include allene, manganallyl, and vinylcarbene ligands, the first two of which have been realized experimentally in research by Adams and coworkers. Theoretical studies suggest that the mechanism for the conversion of the simple alkyne octacarbonyl (MeC₂NMe₂)Mn₂(CO)₈to the dimethylaminomanganaallyl complex Mn₂(CO)₇[μ‐η⁴‐C₃H₃Me₂] involves decarbonylation to the heptacarbonyl and the hexacarbonyl complexes. Subsequent hydrogen migrations then occur through intermediates with C−H−Mn agostic interactions to give the final product. Eight transition states for this mechanistic sequence have been identified with activation energies of ∼20 kcal/mol for the first hydrogen migration and ∼14 kcal/mol for the second hydrogen migration.