He was later to collect the Nobel Prize in Physics in 1966. Kastler taught for close to five years before furthering his career to higher education by joining Faculty of Science at Bordeaux . He later worked as a lecturer at Clermont_Ferrand for two years, then at Bordeaux again, but this time as a professor for two years. In 1941, George Bruhat asked Alfred to abandon his occupation in Germany and join them in Paris where he was to assist in building physics teaching program at Ecole Normale Superieure. Although the post he was offered was provisional, he did accept to take it.
He was later confirmed in 1952 at the Paris Faculty of Sciences when he was allocated an official position. Alfred Kastler is reported to have developed an interest in science in his junior level studies particularly because of his mathematics teachers at that time who greatly influenced his choice. He was later to strengthen his foundation in mathematics when he joined a special mathematics class held by some two influential scientists, Brunold and Mahuet. It was these two who made him secure an entry to the Ecole Normale Superieure.
This college offered a rather friendly environment where one could comfortably study to great depth his field of specialization. Bohrs atom and other interesting concepts of quantum physics were introduced to Alfred by one of his teachers Eugene Bloch. Kastler developed a particular interest in the approach used by Sommerfeld in his analysis of atomic structures and the explanations on the observable spectral lines. Sommerfelds book explained the famous principles of conservation of momentum as applied in the investigation of energy exchange processes between atoms and even radiation by A.
Rubinowicz. Interpretation of various selection rules for example, for azimuthal quantum number and also polarization in the Zeeman effect are traced to this principle. All the research work carried out by Kastler was also stemmed on this principle. Alfred went ahead and even carried out experiments in attempt to elucidate there exist transverse component of the momentum of photons. These experiments failed since he discovered they never existed. This he realized after appreciating the results obtained by R. Frisch who was his predecessor in this field of study.
At the time when Alfred Kastler was appointed to assist professor Pierre Daure back at Bordeaux Faculty of Science, most of his free time was devoted to research work since his duties ten were less strenuous. It was at this time that Professor Daure introduced him into the field of experimental spectroscopy. Alfred studied optical spectrometry specifically, atomic fluorescence and also Raman spectroscopy. During his studies, the luminescence of sodium atoms in the upper atmosphere greatly interested him leading to his discovery of the D line of the twilight sky that could actually get absorbed by the sodium vapor.
He also carried out intensive research at Abisko exposing his experiments to prolonged twilight and together with his colleague, Jean Bricard, he demonstrated that D line is polarized. This is indeed justified if this emission mechanism produced by solar radiation is of the optical resonance type. Alfred remained focused and persistent in his research thereby developing a systematic approach to the consequences of the principal of conservation of angular momentum as observed in optical (light) scattering and also in fluorescence.
During this process, he realized that optical excitation of atoms and especially when done in steps, was a very interesting method in experimental physics since the operator could at will subject different monochromatic sources of radiation to polarization and then observe the atom rise through successive steps depending on the absorbed increased energy amounts. Many other scientists applied various methods to investigate atoms especially at the fundamental state; something was yet to be done about their excited states.
The suggestion to extend investigation methods to the excited states of atoms was made by one renowned scientist, Bitter, who also Kastlers former student. It was then that Kastler and Brossel resolved to use double resonance method. This method was a little bit complicated and involved a combination of the already existing methods of analysis; optical resonance and magnetic resonance. Experiments involving Double resonance involved the use of an r. f field of a corresponding frequency to the interval observed in Zeeman splitting.
This in turn depolarizes polarized ground state resulting into increased or accelerated optical absorption as controlled using a photodiode. Since Brossel had prior knowledge on the study of exited states which he did back at M. I. T and Kastler was an expert in optical pumping, this was a great boost particularly when it came to combining the two methods. Together, they worked to perfect the methods receiving assistance from young energetic intellectuals from Ecole Normale in Paris. Kastler is also reported to have had very stimulating lectures about this particular field.
According to his students, he described atoms and photons in the simplest of ways making them much more interesting than they had imagined, posing new possibilities to be explored further in this field. He considered himself a student and was always eager to be taught and explore new things. No wander he sometimes sat amid the learners keenly following lectures on matrix theory! His analysis in the earlier stages involved the use of mercury atom which he excited optically in the presence of a magnetic field. He observed only selected Zeeman sublevels presented in those exited states.
Of significant interest was the observable selection that still existed even in the absence of magnetic field (zero magnetic fields). Alfred also realized that Fermi and Rasetti had used alternating magnetic field in their experiments on excited atoms but never studied resonance phenomenon of the same. It is thus indeed the polarized light which permits this detection using light of the magnetic resonance of the excited states. In the process of applying double resonance by Jean, Alfred showed that are optically excitated using circularly polarized light enabled the transfer of angular momentum to the atoms.
The French physicist won the respected Nobel Prize for Physics in 1966. This followed his new discovery, development and implementation of methods used in observing Hertzian resonance within atoms. At that time, he was the professor in charge of Laboratory physics at Ecole Normale Superieure. His research work that saw him earn this award initiated the study of atomic structures in greater depths using emitted radiations from the atoms under excitation by light waves or even radio waves. He actually used Optical pumping method to stimulate atoms from their fundamental state other excited states.
This technique is currently utilized to produce spin alignment in a selected gas with specific atoms. For instance, application of circularly polarized light at specific frequencies will initiate transitions from ground state to excited states. The light energy used in the process of stimulating the atoms was greatly re-emitted and thus both maser and laser technologies trace their roots to optical pumping. This technique, though comparatively simple, it is significantly applied in measuring hyperfine splitting effect and even nuclear magnetic moments as exhibited by some suitable atoms.
This forms the fundamental principles behind the operation of a low-field magnetometer and also that of an atomic clock. It is also imperative to appreciate that as Alfred and his team was progressing with their research, several foreign teams reported to have achieved excellent results using techniques that were developed by him. They could actually measurements on nuclear quadruple electric moments as observed in alkali metals among many other discoveries. Alfred Kastler spent most of his research time studying ground and also excited states of atoms.
This brought him a fat harvest of results especially on the quality of the data he obtained together with his team while studying various parameters of an atom. For instance, their data helped them analyze relaxation processes making them determine precise and exact values of nuclear magnetic resonance in the process. Consequently, they made several discoveries involving high-order perturbations where he demonstrated Hertzian resonance shifts in the act of optical irradiation amongst many other phenomenons. His significant contribution to this field of physics was thus worth rewarding.
References L. Allen and J. H. Eberly (1987), Optical Resonance and Two-Level Atoms. Dover Publications, New York Alfred Kastler. (2009). Encyclopedia Britannica. Retrieved April 27, 2009, from http://www. britannica. com/EBchecked/topic/313094/Alfred-Kastler A. Kastler. (1967) , Optical methods for studying Hertzian resonance. Science Harald Klepel and Dieter Suter. ( 1992. ) Transverse Optical pumping with polarization-modulated light. Optics Commun. ,