| 1. |
- Wang, Xiaolin, et al.
(författare)
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Comprehension of the Effect of a Hydroxyl Group in Ancillary Ligand on Phosphorescent Property for Heteroleptic Ir(III) Complexes : A Computational Study Using Quantitative Prediction
- 2017
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 56:15, s. 8986-8995
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Tidskriftsartikel (refereegranskat)abstract
- A new Ir(III) complex (dfpypya)(2)Ir(pic-OH) (2) is theoretically designed by introduction of a simple hydroxyl group into the ancillary ligand on the basis of (dfpypya)(2)Ir(pic) (1) with the aim to get the high efficiency and stable blue-emitting phosphors, where dfpypya is 3-methyl-6-(2',4'-difluoro-pyridinato)pyridazine, pic is picolinate, and pic OH is 3-hydroxypicolinic acid. The other configuration (dfpypya)(2)Ir(pic OH)' (3) is also investigated to compare with 2. The difference between 2 and 3 is whether the intramolecular hydrogen bond is formed in the (dfpypya)(2)Ir(pic OH). The quantum yield is determined by three different methods including the semiquantitative and quantitative methods. To quantitatively determine the quantum yield is still not an easy task to be completed. This work would provide some useful advices to select the suitable method to reliably evaluate the quantum yield. Complex 2 has larger quantum yield and more stability as compared with 1 and 3. The formation of intramolecular hydrogen bond would become a new method to design new phosphor with the desired properties.
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| 2. |
- Zhao, Xiangen, et al.
(författare)
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Ionization Activity Detected During Dark Periods in Long Air Positive Sparks
- 2023
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Ingår i: Journal of Geophysical Research - Atmospheres. - : American Geophysical Union (AGU). - 2169-897X .- 2169-8996. ; 128:10
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Tidskriftsartikel (refereegranskat)abstract
- The dark period in long air gap discharges has been assumed in the literature as the time between consecutive streamer current pulses when ionization and luminosity are absent. These dark periods are also present in natural lightning, in processes such as the inception and propagation of upward positive leaders, the development of needles, as well as transient luminous events in the upper atmosphere. Only recently, faint luminosity has been observed during dark periods, challenging this assumption. This paper aims to study any possible electrical activity during dark periods by means of experiments supported by computer simulation. Therefore, an experimental platform, including low-current measurements, Schlieren and standard photography as well as ultraviolet (UV)-photon detection was used to observe the electrical-optical-thermal characteristics of the dark period. A complementary numerical model was used to estimate the streamer space charge spatial distribution and its drift during dark periods. It is found that faint UV and visible light during the dark period is emitted exactly at the location of the low-density streamer stem channel. This process is accompanied by the generation of an electronic current in the order of hundred microamps to milliamps. The simulation results show that this ionization activity occurs due to strong reduced electric fields in the residual stem channel above 112 Td, which is mainly determined by a combination of applied voltage, space charge distribution, and localized heating. Thus, the presented results show that there is indeed ionization activity during dark periods in long air gaps, which maintains a continuous glow-like discharge.
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