2.Keypoints and Difficulties Keypoints:crystal field;orbital quenching:Jahn-Teller effects Difficulties:crystal field:orbital quenching:Jahn-Teller effects 3.Contents 3.1 Crystal fields 3.1.1 Origin of crystal fields 3.1.2 Orbital quenching 3.1.3 The Jahn-Teller effect 3.2 Magnetic resonance techniques 3.2.1 Nuclear magnetic resonance 4.Teaching method Teaching:Group Discussion:Autodidacticism under the guidance of the teacher 5.Comments Carefully prepare lessons,prepare students and make preparations before class:In the teaching process,we pay attention to cultivating students'creative thinking,take students as the main body and enhance students sense of participation:Correspondingexercises and supplementary exercises after class. Problems: (3.1)A Sc++ion has one electron in the 3d shell.It is in an anisotropic crystal and the crystal field can be written as a potential acting on the 3d electron as Al'z.What are the lowest orbital states of the Sc ion if A>0 and if A0?The spin-orbit coupling A.1s is much smaller than the crystal field When this is included,what are the approximate ground states of the ion,for A <0 and A >0?Discuss the effect on these states of applying a small magnetic field along the z axis and perpendicular to the z axis,and sketch the temperature dependence of the susceptibility. (3.2)Equal point positive charges are placed on each of the six comers of an octahedron.Taking the origin of a set of cartesian coordinates to be at the centre of the octahedron,show that the potential close to the centre is given by where q is the magnitude of each charge and a is the distance between the origin and each charge.2. Keypoints and Difficulties Keypoints: crystal field; orbital quenching; Jahn-Teller effects Difficulties: crystal field; orbital quenching; Jahn-Teller effects 3. Contents 3.1 Crystal fields 3.1.1 Origin of crystal fields 3.1.2 Orbital quenching 3.1.3 The Jahn-Teller effect 3.2 Magnetic resonance techniques 3.2.1 Nuclear magnetic resonance 4. Teaching method Teaching; Group Discussion; Autodidacticism under the guidance of the teacher 5. Comments Carefully prepare lessons, prepare students and make preparations before class; In the teaching process, we pay attention to cultivating students' creative thinking, take students as the main body and enhance students' sense of participation; Corresponding exercises and supplementary exercises after class. Problems： (3.1) A Sc++ ion has one electron in the 3d shell. It is in an anisotropic crystal and the crystal field can be written as a potential acting on the 3d electron as Al2 z. What are the lowest orbital states of the Sc ion if A > 0 and if A < 0? The spin-orbit coupling A.1 • s is much smaller than the crystal field. When this is included, what are the approximate ground states of the ion, for A < 0 and A > 0? Discuss the effect on these states of applying a small magnetic field along the z axis and perpendicular to the z axis, and sketch the temperature dependence of the susceptibility. (3.2) Equal point positive charges are placed on each of the six comers of an octahedron. Taking the origin of a set of cartesian coordinates to be at the centre of the octahedron, show that the potential close to the centre is given by where q is the magnitude of each charge and a is the distance between the origin and each charge