electron spin resonance

电子自旋共振
  • 文章类型: Journal Article
    旧石器时代中期的出现,及其随时间和空间的变化是史前考古学领域的关键问题。在地块中部的东南边缘和罗纳河谷中部的许多地点都有记录,连接北欧和地中海的迁徙路径。日期很好,长地层序列对于了解尼安德特人的动态和灭亡至关重要,以及与该地区智人的潜在互动,例如在Maras岩石收容所(“AbriduMaras”)展示的那个。该遗址的特点是考古遗迹的特殊保存,包括使用放射性碳(14C)的骨骼和使用电子自旋共振结合铀系列(ESR/U系列)的牙齿。使用光学激发的发光来确定沉积沉积物的年代。通过使用贝叶斯建模将新时代与以前的时代相结合,我们能够澄清20万年的占领时间。在CA之间。250和40ka,该遗址被尼安德特人用作长期住所,特别是在三个间冰期:第一个在海洋同位素阶段(MIS)7,在247±34和223±33ka之间,然后在MIS5(在127±17和90±9ka之间)和MIS3(最高39,280calBP)期间反复出现。
    The emergence of the Middle Palaeolithic, and its variability over time and space are key questions in the field of prehistoric archaeology. Many sites have been documented in the south-eastern margins of the Massif central and the middle Rhône valley, a migration path that connects Northern Europe with the Mediterranean. Well-dated, long stratigraphic sequences are essential to understand Neanderthals dynamics and demise, and potential interactions with Homo sapiens in the area, such as the one displayed at the Maras rock shelter (\"Abri du Maras\"). The site is characterised by exceptional preservation of archaeological remains, including bones dated using radiocarbon (14C) and teeth using electron spin resonance combined with uranium series (ESR/U-series). Optically stimulated luminescence was used to date the sedimentary deposits. By combining the new ages with previous ones using Bayesian modelling, we are able to clarify the occupation time over a period spanning 200,000 years. Between ca. 250 and 40 ka, the site has been used as a long-term residence by Neanderthals, specifically during three interglacial periods: first during marine isotopic stage (MIS) 7, between 247 ± 34 and 223 ± 33 ka, and then recurrently during MIS 5 (between 127 ± 17 and 90 ± 9 ka) and MIS 3 (up to 39,280 cal BP).
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  • 文章类型: Journal Article
    给出了三种混合价铜氰化物烷醇胺聚合物的晶体结构,以及热重分析(TGA)和电子自旋共振(ESR)数据。在所有三个结构中,晶体对称中心上的CuII部分由两个链烷醇胺配位,并通过氰化物桥连基团连接两个CuICN链,形成双周期片。所述片通过亲铜CuI-CuI相互作用连接在一起以形成三维网络。在聚[双(μ-3-氨基丙醇合)四-μ-氰基-dicopper(I)dicopper(II)]中,[Cu4(CN)4(C3H8NO)2]n,在图1中,丙醇胺碱失去了它们的羟基H原子,并作为螯合物与两个CuII原子配位,形成通过碱的O原子与CuII原子以正方形平面配位桥接的二聚体CuII部分。ESR谱非常宽,表示两个CuII中心之间的交换。在聚[双(2-氨基丙醇)四-μ-氰基-铜(I)铜(II)]中,[Cu3(CN)4(C3H9NO)2]n,2,和聚[双(2-氨基乙醇)四-μ-氰基-双铜(I)铜(II)],[Cu3(CN)4(CH7NO)2]n,如图3所示,单个CuII原子通过CN桥将CuICN链连接在一起。螯合链烷醇胺不离子化,OH基团在八面体配位的CuII原子的轴向位置形成相当长的键。2和3中CuII的配位几何形状几乎相同,除了2中的Cu-O距离长于3中的Cu-O距离,这可以解释它们的ESR谱有些不同。2和3中的热分解,但不是1中的热分解,始于HCN(g)的损失,这可能与2和3中配体上OH质子的存在有关,而1中不存在OH质子。
    The crystal structures of three mixed-valence copper cyanide alkanolamine polymers are presented, together with thermogravimetric analysis (TGA) and electron spin resonance (ESR) data. In all three structures, a CuII moiety on a crystallographic center of symmetry is coordinated by two alkanolamines and links two CuICN chains via cyanide bridging groups to form diperiodic sheets. The sheets are linked together by cuprophilic CuI-CuI interactions to form a three-dimensional network. In poly[bis(μ-3-aminopropanolato)tetra-μ-cyanido-dicopper(I)dicopper(II)], [Cu4(CN)4(C3H8NO)2]n, 1, propanolamine bases have lost their hydroxyl H atoms and coordinate as chelates to two CuII atoms to form a dimeric CuII moiety bridged by the O atoms of the bases with CuII atoms in square-planar coordination. The ESR spectrum is very broad, indicating exchange between the two CuII centers. In poly[bis(2-aminopropanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu3(CN)4(C3H9NO)2]n, 2, and poly[bis(2-aminoethanol)tetra-μ-cyanido-dicopper(I)copper(II)], [Cu3(CN)4(CH7NO)2]n, 3, a single CuII atom links the CuICN chains together via CN bridges. The chelating alkanolamines are not ionized, and the OH groups form rather long bonds in the axial positions of the octahedrally coordinated CuII atoms. The coordination geometries of CuII in 2 and 3 are almost identical, except that the Cu-O distances are longer in 2 than in 3, which may explain their somewhat different ESR spectra. Thermal decomposition in 2 and 3, but not in 1, begins with the loss of HCN(g), and this can be correlated with the presence of OH protons on the ligands in 2 and 3, which are not present in 1.
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  • 文章类型: Journal Article
    各种研究表明,采用ESR自旋捕获来检测自由基会对散装油对氧化的脆弱性产生有价值的见解。因此,该方法可用于评估和比较不同样品的氧化稳定性。进行这项研究是为了研究在不同温度和加热时间下亚麻籽油中自由基和反式异构体的产生和转化。这些分析表明,在加热至120°C的亚麻籽油中,自由基PBN加合物的峰值水平很明显,而这些水平在90分钟内下降,并且在180°C的较高温度下不存在。自由基PBN加合物在180°C容易降解。亚麻油样品中热诱导的反式异构体的水平随着温度的升高而升高,但在超过240°C的温度下开始部分降解。这些反式异构体的含量检查表明,与12位的双键相比,位于9位和15位的双键对异构化表现出更高的敏感性。此外,k和Ea的值表明,与双TALAs相比,三反式-α-亚麻酸(TALAs)的合成更具挑战性,双TALA比单TALA更具挑战性。这是因为三TALAs具有比单TALAs和双TALAs更高的Ea值。研究表明,将亚麻籽油高温加热会导致自由基和反式异构体的产生。并且PBN自由基加合物在180°C下是不稳定的,并且位置9和15处的双键可以比位置12处的双键更容易异构化。这些结果表明,控制自由基和单TALAs异构体的形成可能是降低食用油加热过程中亚麻酸反式异构体的关键方法。在后续研究中,我们发现VE,VK3、乙基咖啡酸和白藜芦醇对亚麻酸TALAs的形成有显著的抑制作用,添加5%的白藜芦醇的最高抑制率可达30.86%。上述物质可用于亚麻籽油的热处理,以防止TALAs的形成。
    Various studies have demonstrated that employing ESR spin trapping to detect free radicals yields valuable insights into the vulnerability of bulk oils to oxidation. Consequently, this method can be employed to assess and compare the oxidative stability of different samples. This study was conducted to investigate the production and transformation of free radicals and trans isomers in linseed oil when subjected to different temperatures and durations of heating. These analyses revealed that the peak levels of free radicals PBN adducts were evident in linseed oil heated to 120 °C, while these levels decreased within 90 min and were absent at a higher temperature of 180 °C. Free radical PBN adducts were readily degraded at 180 °C. Levels of heat-induced trans isomers rose in linseed oil samples with rising temperatures but began to degrade at temperatures exceeding 240 °C partially. The content examination of these trans isomers revealed that the double bonds located at positions 9 and 15 exhibited a higher susceptibility to isomerization compared to the double bond at position 12. Furthermore, the values of k and Ea indicated that the synthesis of tri-trans-α-linolenic acid (TALAs) was more challenging compared to double-TALAs, and double-TALAs were more challenging than single-TALAs. This was because the tri-TALAs has a higher Ea value than the mono-TALAs and double-TALAs. The study has demonstrated that subjecting linseed oil to high-temperature heating leads to the production of free radicals and trans isomers. And PBN radical adduct is unstable at 180 °C and the double bonds at positions 9 and 15 could be isomerized more easily than that at position 12. These results indicated that controlling the formation of free radicals and single-TALAs isomers may be the key way to reduce the trans isomers of linolenic acid during cooking oil heating. In the follow-up study, we found that VE, VK3, ethyl caffeic acid and resveratrol had significant inhibitory effects on the formation of TALAs of linolenic acid, and the highest inhibitory rate of resveratrol with 5% addition could be reached to 30.86%. The above substances can be applied to the thermal processing of linseed oil to prevent the formation of TALAs.
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  • 文章类型: Journal Article
    使用水热法合成了用于锂离子电池(LIB)的Li3V2(PO4)3阴极,随后在氩气气氛中进行退火以达到最佳性能。X射线衍射分析证实了材料的单相性质,而扫描电子显微镜显示出颗粒状结构,表明均匀的粒度分布,有利于电化学性能。进行了磁测量和电子自旋共振研究,以研究磁特性,证实了相对低浓度和高度均匀分布的四价钒离子(V4+)的存在,这表明原始结构中的锂缺乏值低,样品中的磁性均匀性高,一致的电化学行为的重要因素。对于纯相Li3V2(PO4)3样品,没有任何杂质,如碳或盐,进行了广泛的电化学性能测试。这些测试导致实验发现非常高的锂扩散系数D=1.07×10-10cm2/s,表明优异的离子导电性,并表现出令人印象深刻的稳定性与持续的性能超过1000充电-放电循环的材料。此外,重新锂化的Li3V2(PO4)3(多次电化学循环后)样品使用扫描电子显微镜研究,磁强计和电子自旋共振方法来确定降解的程度。高锂扩散系数的组合,低降解速率和显著的循环稳定性将这种Li3V2(PO4)3材料定位为高级储能应用的有希望的候选材料。
    Li3V2(PO4)3 cathodes for Li-ion batteries (LIBs) were synthesized using a hydrothermal method with the subsequent annealing in an argon atmosphere to achieve optimal properties. The X-ray diffraction analysis confirmed the material\'s single-phase nature, while the scanning electron microscopy revealed a granular structure, indicating a uniform particle size distribution, beneficial for electrochemical performance. Magnetometry and electron spin resonance studies were conducted to investigate the magnetic properties, confirming the presence of the relatively low concentration and highly uniform distribution of tetravalent vanadium ions (V4+), which indicated low lithium deficiency values in the original structure and a high degree of magnetic homogeneity in the sample, an essential factor for consistent electrochemical behavior. For this pure phase Li3V2(PO4)3 sample, devoid of any impurities such as carbon or salts, extensive electrochemical property testing was performed. These tests resulted in the experimental discovery of a remarkably high lithium diffusion coefficient D = 1.07 × 10-10 cm2/s, indicating excellent ionic conductivity, and demonstrated impressive stability of the material with sustained performance over 1000 charge-discharge cycles. Additionally, relithiated Li3V2(PO4)3 (after multiple electrochemical cycling) samples were investigated using scanning electron microscopy, magnetometry and electron spin resonance methods to determine the extent of degradation. The combination of high lithium diffusion coefficients, a low degradation rate and remarkable cycling stability positions this Li3V2(PO4)3 material as a promising candidate for advanced energy storage applications.
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  • 文章类型: Journal Article
    人工细胞器(AnOs)作为补充细胞生化途径的系统备受关注。虽然已知基于聚合物的人工细胞器含有减少活性氧(ROS)的酶,需要控制其酶活性和细胞靶向以促进细胞内ROS解毒的应用未得到充分开发。这里,我们引入了先进的AnOs,其中膜的化学成分支持成孔蜂毒素的插入,使AnO腔和环境之间的分子交换,而包封的乳过氧化物酶(LPO)保持其催化功能。我们表明,AnOs外部的H2O2穿透蜂毒素孔,并被包封的酶迅速降解。由于细胞穿透肽的表面附着促进了细胞对AnOs的摄取,电子自旋共振显示,与非靶向AnOs相比,这些细胞靶向AnOs在细胞内ROS解毒方面显着增强,从而为显著降低细胞氧化应激开辟了新的途径。
    Artificial organelles (AnOs) are in the spotlight as systems to supplement biochemical pathways in cells. While polymersome-based artificial organelles containing enzymes to reduce reactive oxygen species (ROS) are known, applications requiring control of their enzymatic activity and cell-targeting to promote intracellular ROS detoxification are underexplored. Here, we introduce advanced AnOs where the chemical composition of the membrane supports the insertion of pore-forming melittin, enabling molecular exchange between the AnO cavity and the environment, while the encapsulated lactoperoxidase (LPO) maintains its catalytic function. We show that H2O2 outside AnOs penetrates through the melittin pores and is rapidly degraded by the encapsulated enzyme. As surface attachment of cell-penetrating peptides facilitates AnOs uptake by cells, electron spin resonance revealed a remarkable enhancement in intracellular ROS detoxification by these cell-targeted AnOs compared to nontargeted AnOs, thereby opening new avenues for a significant reduction of oxidative stress in cells.
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  • 文章类型: Journal Article
    我们先前的研究表明,由于活性氧(ROS),封装CO2气体的纳米气泡(NBs)具有杀菌活性(Yamaguchi等人。,2020)。这里,我们报告说,通过使用频率为1.7MHz的压电换能器超声辐照碳酸水,可以有效地产生包裹CO2的大量NB。产生的NB的大小小于100纳米,寿命为500小时。用电子自旋共振光谱和荧光光谱法研究了NB悬浮液中ROS的产生。发现主要的ROS是羟基自由基,这与我们之前的观察是一致的。杀菌活性持续至少一周。此外,通过用超声波雾化NB悬浮液产生的雾被证实具有与悬浮液本身相同的杀菌活性。我们相信强者,持续的杀菌活性和自由基产生现象是超声波辐照碳酸水产生的NBs所特有的。我们认为,截留的CO2分子在NB界面与水强烈相互作用,削弱界面,高压CO2气体从这个弱化的界面喷出,产生具有杀菌活性的ROS。
    Our previous study showed that nanobubbles (NBs) encapsulating CO2 gas have bactericidal activity due to reactive oxygen species (ROS) (Yamaguchi et al., 2020). Here, we report that bulk NBs encapsulating CO2 can be efficiently generated by ultrasonically irradiating carbonated water using a piezoelectric transducer with a frequency of 1.7 MHz. The generated NBs were less than 100 nm in size and had a lifetime of 500 h. Furthermore, generation of ROS in the NB suspension was investigated using electron spin resonance spectroscopy and fluorescence spectrometry. The main ROS was found to be the hydroxyl radical, which is consistent with our previous observations. The bactericidal activity lasted for at least one week. Furthermore, a mist generated by atomizing the NB suspension with ultrasonic waves was confirmed to have the same bactericidal activity as the suspension itself. We believe that the strong, persistent bactericidal activity and radical generation phenomenon are unique to NBs produced by ultrasonic irradiation of carbonated water. We propose that entrapped CO2 molecules strongly interact with water at the NB interface to weaken the interface, and high-pressure CO2 gas erupts from this weakened interface to generate ROS with bactericidal activity.
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  • 文章类型: Journal Article
    嵌段共聚物是一类在有序结构中自组装的能力方面特别令人感兴趣的材料。在这种情况下,考虑到分子水平的运动会影响大分子的各种性质,环境与动力学之间的耦合尤其重要。将聚合物与第二大分子混合似乎是研究这些关系的简单方法。在这项工作中,我们研究了聚(甲基丙烯酸甲酯)(PMMA)和由PMMA作为第一嵌段和聚(3-甲基-4-[6-(甲基丙烯酰氧基)-己氧基]-4'-戊氧基偶氮苯)作为第二嵌段组成的嵌段共聚物的共混物。通过电子自旋共振(ESR)光谱研究了这些共混物的弛豫特性,对纳米长度尺度敏感。对共混物的研究结果与共聚物的动态行为有关。在纳米级,这项研究揭示了异质性的存在,具有可用于分子重新定向的缓慢和快速动力学,其进一步通过嵌段共聚物形成超分子结构的能力来调节。对于混合物,仍然检测到纳米级的异质性。然而,观察到PMMA作为共混物的主要组分的存在改变了其动态行为。
    Block copolymers are a class of materials that are particularly interesting with respect to their capability to self-assemble in ordered structures. In this context, the coupling between environment and dynamics is particularly relevant given that movements at the molecular level influence various properties of macromolecules. Mixing the polymer with a second macromolecule appears to be an easy method for studying these relationships. In this work, we studied blends of poly(methyl methacrylate) (PMMA) and a block copolymer composed of PMMA as the first block and poly(3-methyl-4-[6-(methylacryloyloxy)-hexyloxy]-4\'-pentyloxy azobenzene) as the second block. The relaxational properties of these blends were investigated via electron spin resonance (ESR) spectroscopy, which is sensitive to nanometric length scales. The results of the investigations on the blends were related to the dynamic behavior of the copolymers. At the nanoscale, the study revealed the presence of heterogeneities, with slow and fast dynamics available for molecular reorientation, which are further modulated by the ability of the block copolymers to form supramolecular structures. For blends, the heterogeneities at the nanoscale were still detected. However, it was observed that the presence of the PMMA as a major component of the blends modified their dynamic behavior.
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  • 文章类型: Journal Article
    为了创造用于生物医学的新型生物可降解纳米复合材料,包装,和环境有效的吸附剂,通过静电纺丝获得了由聚(3-羟基丁酸酯)(PHB)和氧化石墨烯(GO)组成的超薄复合纤维。结合热特性的超薄纤维的综合研究,动态电子顺磁共振(ESR)探针测量,并进行了扫描电子显微镜(SEM)。结果表明,在添加0.05、0.1、0.3和1%OG时,纤维的形态和几何形状及其热和动态特性取决于复合材料的含量。通过ESR和DSC方法研究了PHB纤维的结晶和无定形结构特征。对于PHB/GO的所有成分,观察到分子迁移率TEMPO探针(τ)和生物聚醚熔化焓(ΔH)的相关时间的非线性依赖性。外部因素对复合纤维结构动力学性能的影响,例如样品在70°C的水介质中的水热暴露和臭氧分解,导致τ和ΔH的极端依赖性,这反映了以相反的方式影响结构的两个过程。水的塑化作用导致PHB无定形区域中通过链取向的热破坏,随后结晶相减少,GO纳米片聚集成同事,减少GO-大分子接触的数量,从而增加了节段性流动性,通过降低τ值来证实。所获得的PHB/GO原纤复合材料应在未来应用于创建具有改善的生物相容性和高阻隔性能的新的治疗和包装系统。
    In order to create new biodegradable nanocomposites for biomedicine, packaging, and environmentally effective adsorbents, ultra-thin composite fibers consisting of poly(3-hydroxybutyrate) (PHB) and graphene oxide (GO) were obtained by electrospinning. Comprehensive studies of ultrathin fibers combining thermal characteristics, dynamic electron paramagnetic resonance (ESR) probe measurements, and scanning electron microscopy (SEM) were carried out. It is shown that at the addition of 0.05, 0.1, 0.3, and 1% OG, the morphology and geometry of the fibers and their thermal and dynamic characteristics depend on the composite content. The features of the crystalline and amorphous structure of the PHB fibers were investigated by the ESR and DSC methods. For all compositions of PHB/GO, a nonlinear dependence of the correlation time of molecular mobility TEMPO probe (τ) and enthalpy of biopolyether melting (ΔH) is observed. The influence of external factors on the structural-dynamic properties of the composite fiber, such as hydrothermal exposure of samples in aqueous medium at 70 °C and ozonolysis, leads to extreme dependencies of τ and ΔH, which reflect two processes affecting the structure in opposite ways. The plasticizing effect of water leads to thermal destruction of the orientation of the pass-through chains in the amorphous regions of PHB and a subsequent decrease in the crystalline phase, and the aggregation of GO nanoplates into associates, reducing the number of GO-macromolecule contacts, thus increasing segmental mobility, as confirmed by decreasing τ values. The obtained PHB/GO fibrillar composites should find application in the future for the creation of new therapeutic and packaging systems with improved biocompatibility and high-barrier properties.
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  • 文章类型: Journal Article
    在需要重症监护的重症患者中,氧化应激的增加在发病机制中起着重要作用。镇静剂广泛用于许多这些患者的镇静。一些镇静剂是已知的抗氧化剂。然而,没有研究评估各种镇静剂对不同自由基的直接清除活性。本研究旨在确定常见的镇静剂(异丙酚,硫喷妥钠,和右美托咪定(DEX))具有使用体外电子自旋共振对各种自由基的直接清除活性。超氧化物,羟基自由基,单线态氧,并测定了一氧化氮(NO)的直接清除活性。所有镇静剂清除不同类型的自由基。DEX,一种新的镇静剂,还清除了羟基自由基。硫喷妥钠清除所有类型的自由基,包括NO,而异丙酚不能清除超氧自由基。在这个回顾性分析中,我们观察到重度颅脑外伤患者服用硫喷妥钠后氧化抗氧化剂标志物的变化.我们确定了临床中使用的各种镇静剂的直接自由基清除活性。此外,我们报道了一例具有代表性的创伤性脑损伤病例,其中硫喷妥钠显著影响氧化应激相关生物标志物.这项研究表明,在未来,含硫喷妥钠的镇静剂可以通过进一步的临床研究重新开发为抗氧化疗法。
    In critically ill patients requiring intensive care, increased oxidative stress plays an important role in pathogenesis. Sedatives are widely used for sedation in many of these patients. Some sedatives are known antioxidants. However, no studies have evaluated the direct scavenging activity of various sedative agents on different free radicals. This study aimed to determine whether common sedatives (propofol, thiopental, and dexmedetomidine (DEX)) have direct free radical scavenging activity against various free radicals using in vitro electron spin resonance. Superoxide, hydroxyl radical, singlet oxygen, and nitric oxide (NO) direct scavenging activities were measured. All sedatives scavenged different types of free radicals. DEX, a new sedative, also scavenged hydroxyl radicals. Thiopental scavenged all types of free radicals, including NO, whereas propofol did not scavenge superoxide radicals. In this retrospective analysis, we observed changes in oxidative antioxidant markers following the administration of thiopental in patients with severe head trauma. We identified the direct radical-scavenging activity of various sedatives used in clinical settings. Furthermore, we reported a representative case of traumatic brain injury wherein thiopental administration dramatically affected oxidative-stress-related biomarkers. This study suggests that, in the future, sedatives containing thiopental may be redeveloped as an antioxidant therapy through further clinical research.
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  • 文章类型: Journal Article
    当系统哈密顿量中的参数连续快速变化时,量子态之间会发生Landau-Zener-Stückelberg-Majorana(LZSM)跃迁。在磁共振中,绝热快速通道中的损失可以使用LZSM跃迁的物理学来理解。LZSM跃迁的大多数处理都忽略了相干的T2移相,however.受到磁共振力显微镜正在进行的工作的激励,我们使用布洛赫方程,坐标变换,和Magnus展开,以在包括T2损耗的固定辐照强度下进行快速场扫描后得出最终磁化强度的表达式。我们的推导引入了一个反演函数,用于数值评估高度振荡积分的傅立叶变换方法。对于低和高辐照强度,给出了最终磁化强度的表达式,有效的时间范围为T2÷T1限制。将分析结果与数值模拟和核磁共振实验进行比较。我们相对简单的计算半定量地再现了T2→0极限中众所周知的LZSM结果。
    Landau-Zener-Stückelberg-Majorana (LZSM) transitions occur between quantum states when parameters in the system\'s Hamiltonian are varied continuously and rapidly. In magnetic resonance, losses in adiabatic rapid passage can be understood using the physics of LZSM transitions. Most treatments of LZSM transitions ignore the T2 dephasing of coherences, however. Motivated by ongoing work in magnetic resonance force microscopy, we employ the Bloch equations, coordinate transformation, and the Magnus expansion to derive expressions for the final magnetization following a rapid field sweep at fixed irradiation intensity that include T2 losses. Our derivation introduces an inversion-function, Fourier transform method for numerically evaluating highly oscillatory integrals. Expressions for the final magnetization are given for low and high irradiation intensity, valid in the T2≪T1 limit. Analytical results are compared to numerical simulations and nuclear magnetic resonance experiments. Our relatively straightforward calculation reproduces semiquantitatively the well known LZSM result in the T2→0 limit.
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