诺奖人物科普篇（二）：C. V. Raman，真理的挑战者，命运的角斗士！

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诺奖人物科普篇

C. V. Raman—敢于挑战真理的勇者

为什么海水是深蓝色的？

英国物理学家瑞利（Lord Rayleigh）曾对此做出解释：深海的蓝色并不是海水的颜色，只不过是天空蓝色被海水反射所致。这个说法曾被科学界的大多数人接受，成为默认的真理。

可是一位印度学者却对此提出质疑，他在前往英国的客轮上通过一套简便的光学仪器对海面进行观测，发现海水的蓝色比天空更深。经过一系列的观察和研究，他向权威真理提出了挑战：海水的颜色并非由天空颜色引起的，而是海水本身的一种性质。

这位印度学者就是拉曼（Chandrasekhara Venkata Raman），出身于印度，科研生涯坎坷波折的拉曼，克服了重重阻碍，怀揣着对科学探索无尽的热忱之心，成为了亚洲首位诺贝尔物理学奖获得者！

图1：印度物理学家拉曼

#1

天赋异禀的物理天才

Chandrasekhara Venkata Raman was born on November 7, 1888 in the city of Trichinopoly, Madras Presidency, British India. Today the city is known as Tiruchirappalli and sits in the Indian state of Tamil Nadu.

Raman’s father was Chandrasekaran Ramanathan Iyer, a teacher of mathematics and physics. At the time of Raman’s birth, the family lived on a low income. Raman was the second of eight children.

Raman’s family were Brahmins, the Hindu caste of priests and scholars. When Raman was four years old his father got a better job, becoming a college lecturer, and the family moved to Waltair (now Visakhapatnam).

From a very young age Raman was interested in science, reading the books his father had used as a student. As he grew older, he started borrowing mathematics and physics books from his father’s college library. Entering his teenage years, he began learning from books his father had bought when he had intended taking a master’s degree in physics.

钱德拉塞卡拉·文卡塔·拉曼于1888年11月7日出生在英属印度马德拉斯管辖区的特里奇诺波利市（今蒂鲁吉拉帕利），位于印度的泰米尔纳德邦。

拉曼的父亲是一名数学和物理学教师。在拉曼出生的时候，这个家庭的收入很低，拉曼是八个孩子中的第二个。

拉曼的家庭是婆罗门：印度教中祭司和学者的种姓。拉曼四岁时，他的父亲找到了一份更好的工作，成为一名大学讲师，全家搬到了瓦尔特尔（今维沙卡帕特南）。

从很小的时候起，拉曼就对科学感兴趣，经常阅读他父亲在学生时代使用过的书籍。随着年龄的增长，他开始从父亲工作的大学图书馆借阅数学和物理书籍。进入青少年时期后，他开始阅读父亲购买的书籍并打算攻读物理学硕士学位。

图2：天赋卓越的物理天才

In 1903, aged just 14, Raman set off for the great city of Madras (now Chennai) to live in a hostel and begin a bachelor’s degree at Presidency College. 

He completed his degree in 1904, winning medals in physics and English. His British lecturers encouraged him to study for a master’s degree in the United Kingdom. Madras’s civil surgeon, however, told him that his health was not robust enough to withstand the British climate; he advised Raman to stay in India.

This was probably excellent advice. The brilliant mathematician Srinivasa Ramanujan, traveled from Madras to work at the University of Cambridge in 1914. Although this led to the creation of some exceptional mathematics, it had a severe impact on Ramanujan’s health.

1903年，年仅14岁的拉曼前往更大的城市马德拉斯（现在的金奈）求学，住在宿舍里，并在加尔各答大学总统学院攻读本科学位。

1904年，拉曼获得本科学位，并在物理学和英文学科表现优异。他的英国讲师鼓励他去英国攻读硕士学位。但是，马德拉斯的医生告诉拉曼，他的健康状况不足以承受英国的气候，建议拉曼留在印度。

这可能是一个很好的建议。因为印度数学家斯里尼瓦瑟·拉马努金（Srinivasa Ramanujan）就曾在1914年从马德拉斯前往剑桥大学工作，虽然这个选择帮助他在数学方面取得了杰出的成就，但也对拉马努金的健康产生了严重影响。

图3：印度数学家Srinivasa Ramanujan

Raman remained at Presidency College to study for his master’s degree. His outstanding potential was recognized, and he was given unlimited access to the laboratories, where he pursued investigations of his own design.

In November 1906, aged 18, Raman had his first academic paper published. He had initially given it to one of his professors to read, but the professor had not bothered. Raman sent his paper directly to Philosophical Magazine and it was accepted. Its title was Unsymmetrical diffraction-bands due to a rectangular aperture.

Following the publication of his second paper in Philosophical Magazine, Raman received a letter from Lord Rayleigh, the eminent British physicist. Rayleigh, unaware that Raman was just a teenage student, sent his letter to “Professor Raman.”

In 1907, aged 19, Raman graduated with a master’s degree in physics, awarded with the highest distinction.

拉曼选择继续留在加尔各答大学总统学院攻读硕士学位。他出色的潜力得到了认可，被允许不受限制地进入实验室，在那里进行他自己的实验设计。

1906年11月，18岁的拉曼发表了他的第一篇学术论文。他最初将论文交给了一位教授阅读，但那位教授并不理会。于是拉曼把他的论文直接寄给了《哲学杂志》，它被接收了。论文的标题是《矩形孔径引起的不对称衍射带》。

当他的第二篇论文在《哲学杂志》上发表后，拉曼收到了著名英国物理学家瑞利勋爵的一封信。瑞利不知道拉曼只是一个十几岁的学生，写信时将他称为"拉曼教授"。

1907年，19岁的拉曼获得了物理学硕士学位，被授予最高荣誉。

图4：英国物理学家瑞利

#2

弃理从政，不忘科研初心

Although Raman was intent upon a scientific career, his brother persuaded him to take the civil service exams. Civil service jobs were highly paid and Raman’s family was deeply in debt.

For 10 years Raman worked as a civil servant in the Indian Finance Department in Calcutta (now Kolkata), rising quickly to a senior position. In his free time he carried out research into the physics of stringed instruments and drums. He did this work at the Indian Association for the Cultivation of Science (IACS).

The IACS had been in a state of hibernation until Raman stumbled upon it and set about reviving it. In addition to his research work, Raman gave public lectures in Calcutta popularizing science.

虽然拉曼一心想从事科学事业，但他的哥哥却劝他参加公务员考试。印度公务员的工资很高，而拉曼的家庭却深陷债务。

拉曼在加尔各答的印度财政部当了10年的公务员，很快就升到了一个高级职位。他把业余时间全部用于研究声学和乐器理论。加尔各答有一所学术机构，叫印度科学教育协会（IACS），拉曼就在这里的实验室开展他的研究。

IACS之前一直处于空闲状态，直到拉曼偶然发现并着手恢复它。除了研究工作之外，拉曼还在加尔各答举办公开讲座，普及科学知识。

图5：印度城市加尔各答

Raman’s part-time research work and his lectures were impressive, establishing his reputation as a highly talented physicist. In 1917, the University of Calcutta sought him out and offered him the Palit Chair of Physics. Although it meant a substantial cut in pay, Raman, now aged 28, accepted – the prospect of devoting all of his time to science was worth more to him than money.

Although it was a research professorship, Raman also chose to give lecture courses: he was an exciting lecturer and he inspired his students.

拉曼的兼职研究工作和演讲令人印象深刻，帮助他建立了一个非常有才华的物理学家的良好声誉。1917年，加尔各答大学邀请他担任物理学教员。尽管这意味着工资的大幅削减，但现年28岁的拉曼还是接受了。对他来说，能将所有时间投入到科学中的前景比金钱更有价值。

虽然是研究型教授职位，但拉曼也选择了讲课：他是一个令人兴奋的讲师，他激励着他的学生。

图6：加尔各答大学

#3

蓝色大海的科学奥秘

One day, in the summer of 1921, Raman was on the deck of a ship in the Mediterranean Sea en route to the Congress of Universities of the British Empire at Oxford. He looked at the beautiful blue color of the Mediterranean Sea and began to doubt Rayleigh’s explanation of its color.

Lord Rayleigh, who had believed the teenage Raman’s papers were the work of a professor, had been one of the great physicists of his day. He had won the 1904 Nobel Prize in Physics.

Rayleigh had correctly explained that the sky looks blue because of a phenomenon now called Rayleigh scattering.

If Earth had no atmosphere, anyone who happened to be around in such circumstances would see a white sun and a black sky. However, this is not what we see, because sunlight interacts with the gases in Earth’s atmosphere.

Rather than coming straight to our eyes from the sun, sunlight is scattered in all directions by the atmosphere. Blue light is scattered most, meaning that it comes to our eyes from everywhere in the sky, therefore the sky looks blue. Yellow and red light are scattered least, so we usually see a yellow sun, and sometimes a red sun.

Rayleigh scattering is elastic. This means that photons of light lose no energy when they interact with gas molecules. The light, therefore, stays the same color.

1921年夏天的一天，拉曼在地中海的客轮甲板上，准备前往牛津参加英联邦大学会议。他看着地中海美丽的蓝色，开始怀疑起瑞利对大海颜色的解释。

瑞利勋爵曾相信少年拉曼的论文是一位教授的作品，他是那个时代伟大的物理学家之一，曾获得1904年诺贝尔物理学奖。

瑞利曾正确地解释说，天空看起来是蓝色的，是瑞利散射作用下的结果。

如果地球没有大气层，在这种情况下，任何碰巧在周围的人都会看到一个白色的太阳和一个黑色的天空。然而这不是我们所看到的，因为太阳光与地球大气层中的气体产生了相互作用。

阳光不是从太阳直射到我们的眼睛，而是被大气层散射到各个方向。蓝光被散射得最多，这意味着它从天空的各个角落来到我们眼前，因此天空看起来是蓝色的。黄光和红光的散射最少，所以我们会看到有时太阳是黄色的，有时太阳是红色的。

瑞利散射是弹性的，这就意味着：光子与气体分子相互作用时不会失去能量。因此，光线会保持相同的颜色。

图7：瑞利散射在地球大气中的表现

When he sailed back to India in September 1921 Raman, an indefatigable scientist, had with him some simple physics apparatus: a prism, a miniature spectroscope, and a diffraction grating. He used these to study the sky and the sea and concluded that the sea was scattering light.

Hence when Rayleigh said the sea’s color is simply a reflection of the sky’s color, he was not wholly correct. Raman reported his findings in a letter to the journal Nature.

When he returned to his laboratory, Raman and his students began an exhaustive program of research into light scattering.

1921年9月，乘船返回印度的途中，拉曼，这位不屈不挠的科学家，带着一些简单的物理仪器：一个棱镜、一个微型分光镜和一个衍射光栅。他用这些仪器观测了天空和大海，并得出结论：大海在散射光线。

因此，瑞利所说的大海的颜色只是天空颜色的反射并不完全正确。拉曼在给《自然》杂志的一封信中报告了他的发现。

回到自己的实验室后，拉曼和他的学生开始了对光散射的详尽研究。

图8：蓝色大海中的科学奥秘

#4

拉曼效应的成功发现

In 1923, Arthur Compton in St. Louis, USA published exciting new work showing that X-rays can lose energy when they interact with electrons. The X-rays donate some of their energy to electrons, then move on carrying less energy. In other words, Compton demonstrated that inelastic scattering is possible.

Compton received the 1927 Nobel Prize in Physics for this discovery, which became known as the Compton effect.

1923年，美国圣路易斯的阿瑟·康普顿发表了令人兴奋的新发现：X射线在与电子相互作用时可以失去能量。X射线会将其部分能量捐献给电子，然后携带较少的能量继续前进。换句话说，康普顿证明非弹性散射是可能的。

康普顿因这一发现获得了1927年诺贝尔物理学奖，该发现也被称为康普顿效应。

图9：物理学家康普顿

Raman and his students continued researching light scattering in gases, liquids, and solids.

They used monochromatic light – sunlight that had been filtered to leave only a single color – and found that a variety of different liquids – sixty of them – did indeed change the color of the light. They first observed this in April 1923, but very weakly.

In 1927, they found a particularly strong color change in light scattered by glycerol (then called glycerine): “…the highly interesting result that the colour of sunlight scattered in a highly purified sample of glycerine was a brilliant green instead of the usual blue.” ——C. V. Raman

Raman’s team observed the effect in gases, crystals, and glass. The effect might have been mistaken for fluorescence, another phenomenon in which light has its color changed, but in Raman’s work the light scattered by liquids was polarized, which ruled out fluorescence.

What came to be known as the Raman effect – a color change accompanied by polarization – had never been seen before. The inelastic scattering at its heart was a further, very strong, confirmation of quantum theory.

而拉曼和他的学生仍在继续研究气体、液体和固体中的光散射。

他们使用单色光（经过过滤只留下单一颜色的阳光），并发现各种不同的液体（其中有60种）确实改变了光的颜色。他们在1923年4月首次观察到这一点，但非常微弱。

1927年，他们发现甘油（当时称为甘油）散射的光线有特别强烈的颜色变化：“非常有趣的结果是，散射在高度纯化的甘油样品中的太阳光颜色是一种明亮的绿色，而不是通常的蓝色。”——C.V.拉曼。

拉曼的团队在气体、晶体和玻璃中都观察到了这种效应。这种效应可能被误认为是荧光（另一种光改变颜色的现象），但是在拉曼的实验中，液体散射的光是偏振的，所以就排除了荧光。

这个后来被称为拉曼效应的发现（伴随着偏振的颜色变化）以前从未被观测到。其核心的非弹性散射是对量子理论的进一步、非常有力的确认。

图10：拉曼效应

The Raman effect is a very small effect compared with Rayleigh scattering. Only about 1 in ten million photons undergoes inelastic scattering.

Raman and his colleague K.S. Krishnan reported their discovery in March 1928 in Nature.

Raman was awarded the 1930 Nobel Prize in Physics for “work on the scattering of light and for the discovery of the effect named after him.”

“It appears to me that this very beautiful discovery which resulted from Raman’s long and patient study of the phenomenon of light scattering is one of the best convincing proofs of the quantum theory.” ——Robert W. Wood

“[The Raman effect], whose explanation agrees so well with quantum theory, will undoubtedly become a vital source in growing our knowledge of the states of atoms or molecules in transitions, between which their characteristic spectra are emitted.”——Niels Bohr

与瑞利散射相比，拉曼效应是一个非常小的效应。一千万个光子中可能只有一个会发生非弹性散射。

拉曼和他的同事K.S. Krishnan于1928年3月在《自然》上报告了他们的发现。

1930年，拉曼因"在光的散射方面的工作和发现以他名字命名的效应"而被授予诺贝尔物理学奖。

"在我看来，在拉曼对光散射现象的长期和耐心研究下产生的这一非常美丽的发现，是量子理论的最佳说服力证明之一。"——罗伯特·威廉姆斯·伍德

"拉曼效应，其解释与量子理论如此吻合，无疑将成为增长我们对原子或分子在转变中的状态认知的重要来源，它们的特征光谱是在这些转变之间发出的。"——尼尔斯-玻尔

图11：正在做研究的拉曼

#5

加冕殊荣，报效祖国

Raman showed that the energy of photons scattered inelastically serves as a ‘fingerprint’ for the substance the light is scattered from. As a result of this, Raman spectroscopy is now commonly used in chemical laboratories all over the world to identify substances. It is also used in medicine to investigate living cells and tissues – even detecting cancers – without causing harm. 

Raman was knighted in 1929 for his discovery of the Raman Effect, becoming Sir Chandrasekhara Venkata Raman.

拉曼还发现：非弹性散射光子的能量可以作为光所散射的物质的"指纹"。因此，拉曼光谱现在在世界各地的化学实验室中被普遍用于识别物质。它也被用于医学，以检测活体细胞和组织（甚至诊断癌症）而不会造成伤害。

1929年，拉曼因发现拉曼效应而被授予爵士称号，成为钱德拉塞卡拉·文卡塔·拉曼爵士。

图12：石墨烯的拉曼光谱

Raman had supreme confidence in his own ability. He was so sure he would win the 1930 Nobel Prize that he booked tickets to Sweden four months before the winner was announced.

In 1933, Raman became the first Indian director of the Indian Institute of Science in Bangalore. In 1947, he became independent India’s first National Professor. In 1948, he founded the Raman Research Institute in Bangalore, where he worked until the end of his life.

Raman was suspicious of governments playing any role in fundamental science, refusing government funding for his work：“I strongly believe that fundamental science cannot be driven by instructional, industrial and government or military pressures. This was the reason why I decided, as far as possible, not to accept money from the government.”

拉曼对自己的能力有极大的信心。他非常确信自己会赢得1930年的诺贝尔奖，以至于在宣布获奖者的前四个月就订好了去瑞典的机票。

1933年，拉曼成为班加罗尔印度科学研究所的第一位印度籍主任。1947年，他成为印度独立后的第一位国家教授。1948年，他在班加罗尔成立了拉曼研究所，在那里一直工作到他生命的最后一刻。

拉曼对政府在基础科学中扮演的角色保持质疑，拒绝政府为他的工作提供资金："我坚信，基础科学不能被教学、工业和政府或军事压力所驱动。这就是我决定尽可能不接受政府资金的原因。"

图13：为祖国科学发展奋斗终生的拉曼

爱因斯坦曾这么形容自己：我没有特别的才能，只有强烈的好奇心。永远保持好奇心的人是永远进步的人。

出生于独立前的印度，少年天才，却一度被迫放弃物理的拉曼，依靠着简单的实验设备，和对科学无尽的探索之心，不盲从权威，不气馁妥协，最终成就了科学史上的一大奇迹，成为了亚洲首位获得诺贝尔物理学奖的科学家。

加冕殊荣的拉曼，仍然选择回到祖国，为科学事业奋斗终生！一个传奇，在这里诞生，也在这里落幕！

原文链接：

https://www.famousscientists.org/c-v-raman/

资料来源：《Famous Scientists》

本文素材部分来源网络，如有侵权请联系删除。

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博士科普，Philosophiae Doctor Science Network，加拿大官方认证非营利性协会，诞生于加拿大滑铁卢大学。致力于普及科学知识，建立国内外科研交流桥梁。