半导体的能带结构如何决定其在光催化水分解中的行为？导带和价带位置起什么作用？
How does a semiconductor's band structure govern its behavior in photocatalytic water splitting, and what roles do the conduction and valence band edges play?
半导体吸收能量大于带隙的光后，电子跃迁到导带、价带留下空穴。要分解水，导带底必须高于 H+/H2 还原电位、价带顶必须低于 O2/H2O 氧化电位，才能分别驱动产氢与产氧。能带位置与带隙宽度共同决定光催化剂的适用范围。
A semiconductor excited by light with energy above its band gap sends electrons to the conduction band and leaves holes in the valence band. For water splitting, the conduction-band edge must be more negative than the H+/H2 reduction potential and the valence-band edge more positive than the O2/H2O oxidation potential to drive H2 and O2 evolution. Band positions and gap width together define the photocatalyst's usable range.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
《物理化学》(傅献彩) 第五版 下册 第 14 章 ; 另见: A. Fujishima & K. Honda, Nature 1972, 238, 37 (Nature)
A. Fujishima & K. Honda, Nature 1972, 238, 37 (Nature) ; see also: 《物理化学》(傅献彩) 第五版 下册 第 14 章
#光催化 #半导体能带 #水分解
传统胶卷摄影的光化学反应是怎样的？
What photochemical reaction underlies traditional film photography?
胶片乳剂中的卤化银（主要是溴化银）吸收光子后，一个溴离子被氧化成溴原子并释放电子，电子被银离子捕获生成银原子，形成不可见的潜影。显影液把含潜影晶体的银离子还原成金属银，把影像放大十亿倍以上；定影液溶解除去未曝光的卤化银，最终留下负像。
In film emulsion, silver halide (mainly AgBr) absorbs a photon: a bromide ion is oxidized to a bromine atom, releasing an electron that reduces an Ag+ ion to silver, forming an invisible latent image. Developer reduces silver ions in exposed crystals to metallic silver, amplifying the image by more than a billion-fold; fixer dissolves the unexposed halide, leaving a negative image.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
《无机化学》光化学章节
Inorganic Chemistry (photochemistry); Encyclopaedia Britannica (photography)
#光解 #卤化银 #潜影
磷光和荧光有什么本质区别？
What is the fundamental difference between phosphorescence and fluorescence?
荧光是激发单重态直接回到单重态基态时发出的光，寿命约纳秒量级，激发光源移开后几乎立即消失。磷光则要经历系间窜越进入自旋不同的三重态，从三重态回到单重态基态在自旋上是被禁阻的，只能以慢得多的速率发生，寿命从微秒到数秒甚至更长。因此夜光材料在黑暗中仍能持续发光。
Fluorescence is light emitted when an excited singlet returns directly to the singlet ground state, with lifetimes on the nanosecond scale, so it vanishes almost immediately when the exciting source is removed. Phosphorescence requires intersystem crossing to a triplet state of different spin; return from the triplet to the singlet ground state is spin-forbidden and proceeds much more slowly, giving lifetimes from microseconds to seconds or longer. That is why glow-in-the-dark materials keep emitting in the dark.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#磷光 #系间窜越 #三重态
什么是量子产率（quantum yield）？它在光化学反应研究中有什么意义？
What is quantum yield, and why is it important in photochemical studies?
量子产率定义为每吸收一个光子所引起的指定化学事件（反应物消耗或产物生成）的数目，可大于 1（链反应）或小于 1（伴随失活）。它是衡量光化学反应效率的核心指标，用于比较光催化剂和反应路径。
Quantum yield is the number of specified chemical events (reactant consumed or product formed) per photon absorbed; it can exceed 1 in chain reactions or be below 1 when deactivation competes. It is the central metric of photochemical efficiency for comparing photocatalysts and pathways.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#量子产率 #光子吸收 #光反应效率
荧光是怎么产生的？为什么荧光笔写的字在紫外灯下特别亮？
How does fluorescence arise, and why does highlighter writing glow under a UV lamp?
荧光物质吸收紫外或短波长可见光后，电子跃迁到激发态，很快（约纳秒级）以辐射形式放出波长更长的光回到基态。荧光笔墨水中的荧光染料吸收紫外光，放出蓝紫色可见光，因此字迹在紫外灯下显得格外明亮。
A fluorescent substance absorbs UV or short-wavelength light, exciting electrons to a higher state, then quickly (within nanoseconds) returns to the ground state by emitting light of longer wavelength. The fluorescent dyes in highlighter ink absorb UV and re-emit blue-violet light, so the writing appears unusually bright under a UV lamp.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#荧光 #激发态 #发光
什么是光敏化（photosensitization）？在光催化中敏化剂起什么作用？
What is photosensitization, and what role does a sensitizer play in photocatalysis?
光敏化指由敏化剂先吸收光进入激发态，再把能量或电子转移给自身几乎不吸光的反应物，从而引发其光化学反应，敏化剂在净反应中不被消耗。在光催化中，敏化剂（如钌联吡啶配合物、有机染料）把体系的可利用光谱拓宽到可见光区，并将激发态能量或电子高效注入底物或半导体导带，从而提高太阳光利用率。
Photosensitization is when a substance that does not itself react absorbs light and transfers energy or electrons to the reacting species to trigger photochemistry. A sensitizer (e.g., a ruthenium complex or organic dye) broadens the absorbed spectrum and efficiently delivers excited-state energy to a substrate or semiconductor.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
傅献彩 等,《物理化学》第5版,高等教育出版社,2005
Fu Xiancai et al., Physical Chemistry, 5th ed., Higher Education Press, 2005
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040167696（按标识回读: 物理化学(第五版)上册）
#光敏化 #敏化剂 #能量转移
紫外-可见吸收光谱的基本原理是什么？吸收峰位置与分子结构有什么关系？
What is the basic principle of UV-Vis absorption spectroscopy, and how does peak position relate to molecular structure?
UV-Vis 光谱测量分子吸收紫外或可见光后电子能级跃迁的强度随波长变化。共轭体系越大、发色团越多，π→π* 跃迁能量越低，吸收峰越红移（波长变长），因此可用于推断共轭结构。
UV-Vis spectroscopy measures how the intensity of electronic transitions changes with wavelength as a molecule absorbs UV or visible light. Larger conjugated systems and more chromophores lower the π→π* transition energy, shifting the peak to longer wavelength (red shift), so it helps infer conjugation.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
《仪器分析》(武汉大学) 第五版 第 7 章
J. M. Hollas, Modern Spectroscopy, 4th ed., Wiley
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2737206W：Modern spectroscopy（首版
#紫外可见光谱 #电子跃迁 #红移
荧光棒为什么会自己发光，而且几乎不发热？
Why does a glow stick emit light without producing much heat?
荧光棒内两种液体混合后，过氧化物氧化荧光染料（如荧光素），把产物激发到高能态；它回落到基态时以光的形式释放能量，这叫化学发光。能量主要变成光而非热，所以荧光棒发光时几乎不升温。
Inside a glow stick, mixing the two liquids lets a peroxide oxidize a fluorescent dye (e.g., fluorescein), exciting the product to a high-energy state; as it relaxes to the ground state it releases energy as light—chemiluminescence. Because the energy becomes light rather than heat, the stick stays cool.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#化学发光 #荧光棒 #荧光素 #过氧化物
红外光谱中，官能团区与指纹区分别提供什么信息？
In infrared spectroscopy, what information do the functional-group region and the fingerprint region provide?
红外光谱中 4000–1300 cm⁻¹ 为特征频率区（官能团区），主要出现 O-H、N-H、C≡C、C=O 等基团的特征伸缩振动，可据此判断分子含有哪些官能团。1300–400 cm⁻¹ 为指纹区，主要来自单键伸缩和骨架弯曲振动，谱形与整个分子骨架密切相关，如同分子「指纹」，常用于区分同分异构体和比对标准谱图。
In infrared spectroscopy the 4000-1300 cm-1 range is the group-frequency (functional-group) region, dominated by characteristic stretching vibrations of O-H, N-H, C(triple)C and C=O, which reveal which functional groups are present. The 1300-400 cm-1 fingerprint region arises mainly from single-bond stretching and skeletal bending, so its pattern reflects the whole molecular framework and, like a fingerprint, is used to distinguish isomers and to match reference spectra.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《仪器分析》(武汉大学) 第五版 第 4 章
N. B. Colthup, L. H. Daly & S. E. Wiberley, Introduction to Infrared and Raman Spectroscopy, 3rd ed., Academic Press
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4437673W：Introduction to infrare
#红外光谱 #官能团区 #指纹区
为什么荧光显微镜中常用 FITC 等荧光染料标记生物分子？斯托克斯位移有什么作用？
Why are fluorescent dyes like FITC commonly used to label biomolecules in fluorescence microscopy, and what role does the Stokes shift play?
FITC 等染料可被特定波长激发并发射波长更长的荧光，实现对生物分子的特异性可视化。斯托克斯位移（发射波长长于激发波长）使发射光与激发光在光谱上分离，便于滤光片滤除背景激发光，提高信噪比。
Dyes like FITC are excited at a specific wavelength and emit longer-wavelength fluorescence, enabling specific visualization of biomolecules. The Stokes shift (emission at longer wavelength than excitation) spectrally separates emission from excitation so filters can remove background, improving signal-to-noise.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《仪器分析》(武汉大学) 第五版 第 11 章
R. P. Haugland, Handbook of Fluorescent Probes and Research Products, Molecular Probes
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL12754463W：HANDBOOK OF FLUORESCEN
#荧光染料 #FITC #斯托克斯位移
为什么老照片靠见光显影成像？
Why do old photos form images by exposure to light?
卤化银（如溴化银）见光分解出银核，显影液把曝光处放大成黑色银粒，定影液溶去未曝光部分，完成影像。
Silver halides (e.g. AgBr) split into silver nuclei on exposure; developer amplifies exposed grains to black silver, fixer removes the rest—forming the image.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#银盐 #显影 #摄影
为什么荧光棒弯一下就会发光？
Why does a glow stick light up when bent?
弯一下让里面的两种液体混在一起，它们反应放出光，但不烫手。这种不用火也能发光的过程，叫做化学发光。
Bending mixes two liquids inside that react and give off light without heat. This way of making light by a chemical reaction, not fire, is called chemiluminescence.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#荧光棒 #发光 #反应