Photochem最新文献_第8页

Optical and Structural Characteristics of Rare Earth-Doped ZnO Nanocrystals Prepared in Colloidal Solution 胶体溶液中制备稀土掺杂ZnO纳米晶体的光学和结构特性

Photochem Pub Date : 2022-07-02 DOI: 10.3390/photochem2030036

M. Toma, O. Selyshchev, Y. Havryliuk, A. Pop, D. Zahn

{"title":"Optical and Structural Characteristics of Rare Earth-Doped ZnO Nanocrystals Prepared in Colloidal Solution","authors":"M. Toma, O. Selyshchev, Y. Havryliuk, A. Pop, D. Zahn","doi":"10.3390/photochem2030036","DOIUrl":"https://doi.org/10.3390/photochem2030036","url":null,"abstract":"ZnO nanocrystals doped with Nd, Gd, and Er were synthesized using a soft chemical process in ambient atmosphere. Pseudospherical and hexagonal nanocrystals (NC) of the wurtzite phase with a mean size of (7.4 ± 1.7) nm were obtained. The presence of rare earth (RE) dopants was confirmed by X-ray fluorescence (XRF) spectroscopy. The ZnO nanocrystals exhibited simultaneously narrow excitonic- and broad trap/surface-related photoluminescence (PL), both of which were affected by doping with RE atoms. Doping reduced the total PL intensity, suppressing the excitonic emission by a greater extent than the broad band PL. Also, doping resulted in a blue shift of the trap/surface-related emission, while the energy of the excitonic peak remained unchanged. Resonant Raman spectra additionally confirmed the wurtzite phase of ZnO NCs and revealed a shift of the A1-LO mode towards lower frequency upon doping that could be caused by the mass effect of RE atoms, point defects, and increases in charge carrier concentration. Fitting of the spectra with Voigt profiles showed better results with two surface optical (SO) phonon modes that were previously theoretically predicted for the wurtzite ZnO phase. The influence of RE doping on PL and Raman spectra can be explained by the incorporation of RE ions into the ZnO nanostructures, where the dopants act as non-radiative defects.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47132643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Pharmaceutical Micropollutant Treatment with UV–LED/TiO2 Photocatalysis under Various Lighting and Matrix Conditions 不同光照和基质条件下UV–LED/TiO2光催化处理药物微污染物

Photochem Pub Date : 2022-07-01 DOI: 10.3390/photochem2030035

Monika R. Snowdon, R. Liang, Jocelyn C. Van Leeuwen, Olivia M. Schneider, Abrar A. Khan, L. C. Li Chun Fong, N. Zhou, M. Servos

{"title":"Pharmaceutical Micropollutant Treatment with UV–LED/TiO2 Photocatalysis under Various Lighting and Matrix Conditions","authors":"Monika R. Snowdon, R. Liang, Jocelyn C. Van Leeuwen, Olivia M. Schneider, Abrar A. Khan, L. C. Li Chun Fong, N. Zhou, M. Servos","doi":"10.3390/photochem2030035","DOIUrl":"https://doi.org/10.3390/photochem2030035","url":null,"abstract":"The persistence of pharmaceuticals and personal care products (PPCPs) in water has been a cause for concern for several years. Many studies have successfully used TiO2/UV photocatalysis to remove these compounds from water. In order to optimize these systems for large-scale water treatment, the effects of the reaction matrix, methods to improve energy efficiency, and methods for easy catalyst separation must be considered. The following study examines the photocatalytic degradation of a cocktail of 18 PPCPs using a porous titanium–titanium dioxide membrane and the effect of solution pH on kinetic rate constants. The addition of methanol to the reaction—commonly used as a carrier solvent—had a significant effect on kinetic rate constants even at low concentrations. Solution pH was also found to influence kinetic rate constants. Compounds had higher kinetic rate constants when they were oppositely charged to the membrane at experimental pH as opposed to similarly charged, suggesting that electrostatic forces have a significant effect. The controlled periodic illumination of UV–LEDs was also investigated to increase photonic efficiency. The dual-frequency light cycle used did not cause a decrease in degradation for many compounds, successfully increasing the photonic efficiency without sacrificing performance.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47926978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Probing the Local Polarity in Biocompatible Nanocarriers with Solvatofluorochromism of a 4-Carbazole-1,8-naphthalimide Dye 用4-咔唑-1,8-萘酰亚胺染料的溶剂荧光性探测生物相容性纳米载体的局部极性

Photochem Pub Date : 2022-06-24 DOI: 10.3390/photochem2030034

Ana M. Diniz, R. Cruz, J. Avó

引用次数: 2

Antibacterial Activity of In Situ Generated Silver Nanoparticles in Hybrid Silica Films 原位生成的纳米银在杂化二氧化硅膜中的抗菌活性

Photochem Pub Date : 2022-06-23 DOI: 10.3390/photochem2030033

S. Pal, R. Nisi, A. Licciulli

{"title":"Antibacterial Activity of In Situ Generated Silver Nanoparticles in Hybrid Silica Films","authors":"S. Pal, R. Nisi, A. Licciulli","doi":"10.3390/photochem2030033","DOIUrl":"https://doi.org/10.3390/photochem2030033","url":null,"abstract":"Herein we present silver nanoparticles (AgNPs)-doped inorganic–organic hybrid silica films on glass and polypropylene substrates. A hybrid inorganic–organic silica sol in alcoholic medium was prepared at room temperature using TEOS, GLYMO, and APTES. Silver nanoparticles were generated in situ within the hybrid silica sol. AgNPs-SiO2 film was obtained by dip coating method following drying at 80 °C. FTIR spectra shows several vibrational bands of the hybrid silica network and amine functionalization. AgNPs formation was observed from the XRD spectra of the dried film. UV–Visible spectra show sharp surface plasmon resonance (SPR) band centered at 412 nm arising from the evenly distributed silver nanoparticle inside the silica film that was supported by morphological characterization. Both the coated films showed good antibacterial activity against E. coli bacterial strain by forming a zone of inhibition in the agar diffusion test. The antibacterial efficiency for coated glass and polypropylene was 72.5% and 83.75%. This coating approach provides a straight-forward solution to prepare antibacterial coatings on various substrates especially on plastics, where low temperature processing is necessary.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42698673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

UPS, XPS, NEXAFS and Computational Investigation of Acrylamide Monomer UPS、XPS、NEXAFS及丙烯酰胺单体的计算研究

Photochem Pub Date : 2022-06-22 DOI: 10.3390/photochem2030032

L. Evangelisti, S. Melandri, F. Negri, M. Coreno, K. Prince, A. Maris

引用次数: 3

Phototransformations of 2,3-Diamino-2-Butenedinitrile (DAMN) Monomers Isolated in Low-Temperature Argon Matrix 低温氩气基质中分离的2,3-二氨基-2-丁腈(DAMN)单体的光转化

Photochem Pub Date : 2022-06-16 DOI: 10.3390/photochem2020031

I. Reva, H. Rostkowska, L. Lapinski

引用次数: 0

UV-Vis Spectrophotometer as an Alternative Technique for the Determination of Hydroquinone in Vinyl Acetate Monomer 紫外-可见分光光度法测定醋酸乙烯单体中对苯二酚

Photochem Pub Date : 2022-06-15 DOI: 10.3390/photochem2020030

Md Al Mamunur Rashid, Mofizur Rahman, A. Mahmud, A. Morshed, M. Haque, M. Hossain

{"title":"UV-Vis Spectrophotometer as an Alternative Technique for the Determination of Hydroquinone in Vinyl Acetate Monomer","authors":"Md Al Mamunur Rashid, Mofizur Rahman, A. Mahmud, A. Morshed, M. Haque, M. Hossain","doi":"10.3390/photochem2020030","DOIUrl":"https://doi.org/10.3390/photochem2020030","url":null,"abstract":"As an appropriate quantity of hydroquinone (HQ) is essential to safeguard inhibition characteristics by eliminating the risk of self-polymerization of vinyl acetate monomer (VAM), the determination of the HQ content in VAM is very crucial to ensure the stability of VAM during storage and transportation as well as to achieve the possibility of a proper polymerization reaction. In this study, a simple, cheap, time-saving, and easy method has been developed by which the HQ content in VAM can be measured quickly based on the measurement of UV-Vis absorbance of the HQ content at 293 nm using methanol as a blank. No color development is required for this determination process, and the HQ content in the VAM can be measured directly without any further processing. The limit of detection, limit of quantification, linearity range, accuracy, precision, robustness, and measurement uncertainty of this method have been measured and analyzed and found to be within the acceptable limit and range. The method shows linearity within 0.36–25.0 ppm HQ content in the solution range with a regression coefficient of 0.9999, a relative spike recovery of 101.35%, precision of 1.36%, relative bias of 0.55%, and robustness with a temperature variation of −5 °C.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42290976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins 花青素黄离子类似物的荧光和磷光

Photochem Pub Date : 2022-06-08 DOI: 10.3390/photochem2020029

G. T. Silva, Cássio A. P. Silva, Karen M. Silva, R. Pioli, T. S. Costa, Vinícius V. Marto, A. Freitas, Jennifer Rozendo, Lucas M. O. S. Martins, Victor F. Cavalcante, Liuqing Sun, A. Aquino, Vânia M. T. Carneiro, F. Quina

{"title":"Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins","authors":"G. T. Silva, Cássio A. P. Silva, Karen M. Silva, R. Pioli, T. S. Costa, Vinícius V. Marto, A. Freitas, Jennifer Rozendo, Lucas M. O. S. Martins, Victor F. Cavalcante, Liuqing Sun, A. Aquino, Vânia M. T. Carneiro, F. Quina","doi":"10.3390/photochem2020029","DOIUrl":"https://doi.org/10.3390/photochem2020029","url":null,"abstract":"Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44760690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Conformational Structure, Infrared Spectra and Light-Induced Transformations of Thymol Isolated in Noble Gas Cryomatrices 稀有气体低温基质中胸腺嘧啶的构象结构、红外光谱和光诱导转化

Photochem Pub Date : 2022-06-07 DOI: 10.3390/photochem2020028

A. Lopes Jesus, Cláudio M. Nunes, I. Reva

{"title":"Conformational Structure, Infrared Spectra and Light-Induced Transformations of Thymol Isolated in Noble Gas Cryomatrices","authors":"A. Lopes Jesus, Cláudio M. Nunes, I. Reva","doi":"10.3390/photochem2020028","DOIUrl":"https://doi.org/10.3390/photochem2020028","url":null,"abstract":"The conformational space of the natural product thymol (2-isopropyl-5-methylphenol) was investigated using quantum chemical calculations at the B3LYP and MP2 levels, which revealed the existence of four types of conformers differing in the orientation of the isopropyl and hydroxyl groups. Thymol monomers were isolated in noble gas (Ar and Xe) matrices (at 15 K) and characterized by IR spectroscopy. With the support of B3LYP harmonic vibrational calculations, the two most stable trans-OH-conformers, differing in the isopropyl orientation, were identified in the cryomatrices. The two less stable cis-OH conformers were not detected as they shall undergo fast tunneling to the most stable ones. Annealing experiments in a Xe matrix up to 75 K did not lead to any conversion between the two isolated conformers, which is in accordance with the significative energy barrier computed for rotamerization of the bulky isopropyl group (~24 kJ mol−1). Vibrational excitation promoted by broadband or by narrowband irradiation, at the 2ν(OH) frequencies of the isolated conformers, did not lead to any conversion either, which was interpreted in terms of a more efficient energy transfer to the hydroxyl rotamerization (associated with a lower energy barrier and a light H-atom) than to the isopropyl rotamerization coordinate. Broadband UV irradiation experiments (λ > 200 nm) led to a prompt transformation of matrix isolated thymol, with spectroscopic evidence suggesting the formation of isomeric alkyl-substituted cyclohexadienones, Dewar isomers and open-chain conjugated ketenes. The photochemical mechanism interpretation concords with that reported for analogous phenol derivatives.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48500104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Photochemistry of Metal Nitroprussides: State-of-the-Art and Perspectives 金属硝基苯的光化学：现状和展望

Photochem Pub Date : 2022-05-31 DOI: 10.3390/photochem2020027

P. M. Crespo, O. F. Odio, E. Reguera

{"title":"Photochemistry of Metal Nitroprussides: State-of-the-Art and Perspectives","authors":"P. M. Crespo, O. F. Odio, E. Reguera","doi":"10.3390/photochem2020027","DOIUrl":"https://doi.org/10.3390/photochem2020027","url":null,"abstract":"This contribution summarizes the current state in the photochemistry of metal nitroprussides, which is dominated by the electronic structure of the nitrosyl group. From the combination of p orbitals of the nitrogen and oxygen atoms in the NO+ ligand, a π*NO molecular orbital of relatively low energy is formed, which has π*2px and π*2py character. This is a double degenerate orbital. When the nitrosyl group is found coordinated to the iron atom in the nitroprusside ion, the availability of that low energy π*NO orbital results in light-induced electronic transitions from the iron atom dxy, dxz and dyz orbitals, 2b2 (xy) → 7e (π*NO) and 6e (xz,yz) → 7e (π*NO), which are observed at 498 and 394 nm, respectively. These light-induced transitions and the possibility of NO isomer formation dominate the photochemistry of metal nitroprussides. In this feature paper, we discuss the implications of such transitions in the stability of coordination compounds based on the nitroprusside ion in the presence of water molecules for both 3D and 2D structures, including the involved degradation mechanisms. These photo-induced electronic transitions modify the physical and functional properties of solids where the nitroprusside ion forms part of their structure and appear as an opportunity for tuning their magnetic, electrical, optical and as energy-applied materials, for instance. This contribution illustrates these opportunities with results from some recently reported studies, and possible research subjects, even some not explored, are mentioned.","PeriodicalId":74440,"journal":{"name":"Photochem","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49159353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1