Modeling the Unresolved NIR–MIR SEDs of Local (z < 0.1) QSOs

To study the nuclear (≲1 kpc) dust of nearby (z < 0.1) quasi-stellar objects (QSOs), we obtained new near-infrared (NIR) high angular resolution (∼0.″3) photometry in the H and Ks bands for 13 QSOs with available mid-infrared (MIR) high angular resolution spectroscopy (∼7.5–13.5 μm). We find that in most QSOs, the NIR emission is unresolved. We subtract the contribution from the accretion disk, which decreases from NIR (∼35%) to MIR (∼2.4%). We also estimate these percentages assuming a bluer accretion disk and find that the contribution in the MIR is nearly seven times larger. We find that the majority of objects (64%, 9/13) are better fitted by the disk+wind H17 model, while others can be fitted by the smooth F06 (14%, 2/13), clumpy N08 (7%, 1/13), clumpy H10 (7%, 1/13), and two-phase media S16 (7%, 1/13) models. However, if we assume the bluer accretion disk, the models fit only 2/13 objects. We measured two NIR-to-MIR spectral indexes, α NIR−MIR(1.6–8.7 μm) and α NIR−MIR(2.2–8.7 μm), and two MIR spectral indexes, α MIR(7.8–9.8 μm) and α MIR(9.8–11.7 μm), from models and observations. From observations, we find that the NIR-to-MIR spectral indexes are ∼−1.1, and the MIR spectral indexes are ∼−0.3. Comparing the synthetic and observed values, we find that none of the models simultaneously match the measured NIR-to-MIR and 7.8–9.8 μm slopes. However, we note that measuring α MIR(7.8–9.8 μm) on the starburst-subtracted Spitzer/IRS spectrum gives values of the slopes (∼−2) that are similar to the synthetic values obtained from the models.

Deep NIR-I Emissive Iridium(III) Complex Bearing D-A Ligand: Synthesis, Photophysical Properties and DFT/TDDFT Calculation

Near-infrared (NIR) phosphorescent iridium(III) complexes have been demonstrated to possess photophysical properties superior to those of traditional NIR dyes. However, the NIR emission wavelength is restricted in the range of 700–800 nm. For realizing deeper NIR emission, a novel type of iridium(III) complex was designed and synthesized in this work. The main ligand of the iridium(III) complex was constructed using a donor-acceptor structure containing benzothiophene as the donor and quinoxaline as the acceptor. The β-diketone derivative was chosen as the auxiliary ligand owing to its symmetrical structure and p-donating character. The complex exhibits deep NIR-I phosphorescence (764 nm in CH2Cl2, 811 nm in aqueous solution) and broad full width at half maximum (108 nm in CH2Cl2, 154 nm in aqueous solution). Theoretical calculations based on the density function and time-dependent density function were carried out to support the experimental data. Moreover, in vitro biological performance of the complex was determined as well. This work supports the possibility that via a systematic transformation between the D and A units, the photophysical performance of NIR emissive iridium(III) complexes can be greatly improved.