Browsing by Author "Harrison JA"

Now showing 1 - 6 of 6
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    Bis-Anagostic Structures in N,N’-Chelate Ligand Complexes of Palladium(II)
    (Wiley-VCH Verlag, 2022-04) Sajjad MA; Schwerdtfeger P; Cai Y; Waters JM; Harrison JA; Nielson AJ
    Reaction of N,N’-dibenzylidene-2,2-dimethylpropylenediamine with Pd(OAc)2 produces essentially one product which NMR spectroscopy indicates has a bis-anagostic structure. A density functional theory (DFT) calculation shows that in the square planar structure, both aromatic rings lie above the coordination plane with close approaches of two ortho-C−H bond hydrogens to both the Pd centre and the two acetato ligand coordinating oxygen atoms. N,N’-dibenzylideneethylenediamine reacts with Pd(OAc)2 similarly where a bis-anagostic structure is indicated by NMR spectroscopy and a DFT calculation shows an energy preference for an above plane positioning of the two aromatic rings. N,N,N’,N’-tetrabenzylethylenediamine reacts with Pd(OAc)2 to give a structure which X-ray crystallography shows two benzyl phenyl groups lie above and below the coordination plane respectively.
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    Color Tunable Emission and Oxygen Sensing from a Discrete Europium−Pyrene Assembly
    (Wiley-VCH GmbH, 2023-08-14) O'Neil AT; Pope J; Harrison JA; Kitchen JA
    We report the synthesis of a new pyrene, dipicolinic acid-based ligand (L1H) and its corresponding multi-emissive and multifunctional europium complex [Eu(L1)3] that is capable of single component color switchable emission from red to blue and also white. At high concentration (10 mM) the single component system results in near pure white emission (CIE coordinates x,y=0.329, 0.324). Furthermore, the system showed ratiometric oxygen sensing with oxygen significantly quenching the pyrene centered emission but not the Eu3+ emission, resulting in an overall emission color change from blue to red on increasing oxygen content.
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    In-situ optical density sensor
    (2017-04-04) Harrison JA; Saraswat M; Grand R; Noble FK; Gehlen L; Woods MA; Bartho S
    The present invention relates to optical measurement devices and systems, and methods of using these systems and devices, and more particularly but not exclusively it relates to a system and apparatus adapted to measure optical properties in-situ.
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    Ultra-thin films of amphiphilic lanthanide complexes: multi-colour emission from molecular monolayers
    (Royal Society of Chemistry, 2021-08-21) O'Neil AT; Harrison JA; Kitchen JA
    We report the synthesis and Langmuir-Blodgett deposition of 4 brightly emissive lanthanide amphiphiles that can be co-deposited to give multi-emissive ultra-thin films where two, three and four distinct lanthanide emission profiles are observed. To the best of our knowledge, this is the first report of a four-component emissive Langmuir-Blodgett film.
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    Ultrafast UV Luminescence of ZnO Films: Sub-30 ps Decay Time with Suppressed Visible Component
    (Wiley-VCH GmbH, 2024-05-10) Cadatal-Raduban M; Olejníček J; Hibino K; Maruyama Y; Písaříková A; Shinohara K; Asaka T; Lebedová Volfová L; Kohout M; Jiaqi Z; Akabe Y; Nakajima M; Harrison JA; Hippler R; Sarukura N; Ono S; Hubička Z; Yamanoi K
    Ultrafast sub-100 picosecond luminescence is vital in many applications involving ultrafast events and time-of-flight systems. Materials exhibiting fast luminescence, such as barium fluoride (BaF2) and zinc oxide (ZnO), also suffer from an intrinsically slow nanosecond (ns) to microsecond (µs) luminescence. Here, 2.2 micrometer (µm)- to 5.7 µm-thick undoped ZnO films on soda-lime glass (SLG) substrates without a buffer layer by a hybrid pulsed reactive magnetron sputtering operating in the medium-frequency range (MF magnetron) assisted by an electron cyclotron wave resonance (ECWR) plasma is deposited. The undoped ZnO films exhibited superior optical properties characterized by intense ultraviolet (UV) luminescence, unprecedented ultrafast decay times, and for the case of MF+ECWR-deposited films, suppressed defect-related visible luminescence. The 2.2 µm-thick MF-deposited film exhibited the fastest 9-ps decay time at room temperature. The impressive properties of the films are attributed to the use of advanced deposition technology with properly tuned plasma parameters, especially a high degree of dissociation of molecular oxygen together with an increased proportion of activated zinc particles, leading to a higher deposition rate, better crystallinity, fewer defects, and a lower proportion of oxygen vacancies. These films will pave the way toward the development of time-of-flight detectors, high-resolution nuclear imaging cameras, and high-rate ultrafast timing devices.
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    Ultraviolet-C Photoresponsivity Using Fabricated TiO2 Thin Films and Transimpedance-Amplifier-Based Test Setup
    (MDPI (Basel, Switzerland), 2022-11) Cadatal-Raduban M; Pope J; Olejníček J; Kohout M; Harrison JA; Hasan SMR; Torres ML; De Luca AC; Mourka A
    We report on fabricated titanium dioxide (TiO2) thin films along with a transimpedance amplifier (TIA) test setup as a photoconductivity detector (sensor) in the ultraviolet-C (UV-C) wavelength region, particularly at 260 nm. TiO2 thin films deposited on high-resistivity undoped silicon-substrate at thicknesses of 100, 500, and 1000 nm exhibited photoresponsivities of 81.6, 55.6, and 19.6 mA/W, respectively, at 30 V bias voltage. Despite improvements in the crystallinity of the thicker films, the decrease in photocurrent, photoconductivity, photoconductance, and photoresponsivity in thicker films is attributed to an increased number of defects. Varying the thickness of the film can, however, be leveraged to control the wavelength response of the detector. Future development of a chip-based portable UV-C detector using TiO2 thin films will open new opportunities for a wide range of applications.