吀栀攀 渀甀挀氀攀椀 漀昀 洀愀渀礀 攀氀攀洀攀渀琀愀氀 椀猀漀琀漀瀀攀猀 栀愀瘀攀 愀 挀栀愀爀愀挀琀攀爀椀猀琀椀挀 猀瀀椀渀 ⠀䤀⤀⸀ 匀漀洀攀 渀甀挀氀攀椀 栀愀瘀攀 椀渀琀攀最爀愀氀 猀瀀椀渀猀 ⠀攀⸀最⸀ 䤀 㴀 Ⰰ ㈀Ⰰ ㌀ ⸀⸀⸀⸀⤀Ⰰ 猀漀洀攀 栀愀瘀攀 昀爀愀挀琀椀漀渀愀氀 猀瀀椀渀猀 ⠀攀⸀最⸀ 䤀 㴀 ⼀㈀Ⰰ ㌀⼀㈀Ⰰ 㔀⼀㈀ ⸀⸀⸀⸀⤀Ⰰ 愀渀搀 愀 昀攀眀 栀愀瘀攀 渀漀 猀瀀椀渀Ⰰ 䤀 㴀 ⠀攀⸀最⸀ ㈀䌀Ⰰ 㘀伀Ⰰ ㌀㈀匀Ⰰ ⸀⸀⸀⸀⤀⸀ 䤀猀漀琀漀瀀攀猀 漀昀 瀀愀爀琀椀挀甀氀愀爀 椀渀琀攀爀攀猀琀 愀渀搀 甀猀攀 琀漀 漀爀最愀渀椀挀 挀栀攀洀椀猀琀猀 愀爀攀 䠀Ⰰ ㌀䌀Ⰰ 㤀䘀 愀渀搀 ㌀倀Ⰰ 愀氀氀 漀昀 眀栀椀挀栀 栀愀瘀攀 䤀 㴀 ⼀㈀⸀ 匀椀渀挀攀 琀栀攀 愀渀愀氀礀猀椀猀 漀昀 琀栀椀猀 猀瀀椀渀 猀琀愀琀攀 椀猀 昀愀椀爀氀礀 猀琀爀愀椀最栀琀昀漀爀攀眀愀爀搀Ⰰ 漀甀爀 搀椀猀挀甀猀猀椀漀渀 漀昀 渀洀爀 眀椀氀氀 戀攀 氀椀洀椀琀攀搀 琀漀 琀栀攀猀攀 愀渀搀 漀琀栀攀爀 䤀 㴀 ⼀㈀ 渀甀挀氀攀椀⸀
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The following features lead to the nmr phenomenon:㰀⼀瀀㸀㰀瀀㸀
1. A spinning charge generates a magnetic field, as shown by the animation on the right.吀栀攀 爀攀猀甀氀琀椀渀最 猀瀀椀渀ⴀ洀愀最渀攀琀 栀愀猀 愀 洀愀最渀攀琀椀挀 洀漀洀攀渀琀 ⠀밀⤀ 瀀爀漀瀀漀爀琀椀漀渀愀氀 琀漀 琀栀攀 猀瀀椀渀⸀
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2. In the presence of an external magnetic field (B0), two spin states exist, +1/2 and -1/2.吀栀攀 洀愀最渀攀琀椀挀 洀漀洀攀渀琀 漀昀 琀栀攀 氀漀眀攀爀 攀渀攀爀最礀 ⬀⼀㈀ 猀琀愀琀攀 椀猀 愀氀氀椀最渀攀搀 眀椀琀栀 琀栀攀 攀砀琀攀爀渀愀氀 昀椀攀氀搀Ⰰ 戀甀琀 琀栀愀琀 漀昀 琀栀攀 栀椀最栀攀爀 攀渀攀爀最礀 ⴀ⼀㈀ 猀瀀椀渀 猀琀愀琀攀 椀猀 漀瀀瀀漀猀攀搀 琀漀 琀栀攀 攀砀琀攀爀渀愀氀 昀椀攀氀搀⸀ 一漀琀攀 琀栀愀琀 琀栀攀 愀爀爀漀眀 爀攀瀀爀攀猀攀渀琀椀渀最 琀栀攀 攀砀琀攀爀渀愀氀 昀椀攀氀搀 瀀漀椀渀琀猀 一漀爀琀栀⸀
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3. The difference in energy between the two spin states is dependent on the external magnetic field strength, and is always very small. The following diagram illustrates that the two spin states have the same energy when the external field is zero, but diverge as the field increases. At a field equal to Bx a formula for the energy difference is given (remember I = 1/2 and ¼ is the magnetic moment of the nucleus in the field).
Strong magnetic fields are necessary for nmr spectroscopy. The international unit for magnetic flux is the tesla (T). The earth's magnetic field is not constant, but is approximately 10-4 T at ground level. Modern nmr spectrometers use powerful magnets having fields of 1 to 20 T. Even with these high fields, the energy difference between the two spin states is less than 0.1 cal/mole. To put this in perspective, recall that infrared transitions involve 1 to 10 kcal/mole and electronic transitions are nearly 100 time greater.䘀漀爀 渀洀爀 瀀甀爀瀀漀猀攀猀Ⰰ 琀栀椀猀 猀洀愀氀氀 攀渀攀爀最礀 搀椀昀昀攀爀攀渀挀攀 ⠀鐀䔀⤀ 椀猀 甀猀甀愀氀氀礀 最椀瘀攀渀 愀猀 愀 昀爀攀焀甀攀渀挀礀 椀渀 甀渀椀琀猀 漀昀 䴀䠀稀 ⠀ 㘀 䠀稀⤀Ⰰ 爀愀渀最椀渀最 昀爀漀洀 ㈀ 琀漀 㤀 䴀稀Ⰰ 搀攀瀀攀渀搀椀渀最 漀渀 琀栀攀 洀愀最渀攀琀椀挀 昀椀攀氀搀 猀琀爀攀渀最琀栀 愀渀搀 琀栀攀 猀瀀攀挀椀昀椀挀 渀甀挀氀攀甀猀 戀攀椀渀最 猀琀甀搀椀攀搀⸀ 䤀爀爀愀搀椀愀琀椀漀渀 漀昀 愀 猀愀洀瀀氀攀 眀椀琀栀 爀愀搀椀漀 昀爀攀焀甀攀渀挀礀 ⠀爀昀⤀ 攀渀攀爀最礀 挀漀爀爀攀猀瀀漀渀搀椀渀最 攀砀愀挀琀氀礀 琀漀 琀栀攀 猀瀀椀渀 猀琀愀琀攀 猀攀瀀愀爀愀琀椀漀渀 漀昀 愀 猀瀀攀挀椀昀椀挀 猀攀琀 漀昀 渀甀挀氀攀椀 眀椀氀氀 挀愀甀猀攀 攀砀挀椀琀愀琀椀漀渀 漀昀 琀栀漀猀攀 渀甀挀氀攀椀 椀渀 琀栀攀 ⬀⼀㈀ 猀琀愀琀攀 琀漀 琀栀攀 栀椀最栀攀爀 ⴀ⼀㈀ 猀瀀椀渀 猀琀愀琀攀⸀ 一漀琀攀 琀栀愀琀 琀栀椀猀 攀氀攀挀琀爀漀洀愀最渀攀琀椀挀 爀愀搀椀愀琀椀漀渀 昀愀氀氀猀 椀渀 琀栀攀 爀愀搀椀漀 愀渀搀 琀攀氀攀瘀椀猀椀漀渀 戀爀漀愀搀挀愀猀琀 猀瀀攀挀琀爀甀洀⸀ 一洀爀 猀瀀攀挀琀爀漀猀挀漀瀀礀 椀猀 琀栀攀爀攀昀漀爀攀 琀栀攀 攀渀攀爀最攀琀椀挀愀氀氀礀 洀椀氀搀攀猀琀 瀀爀漀戀攀 甀猀攀搀 琀漀 攀砀愀洀椀渀攀 琀栀攀 猀琀爀甀挀琀甀爀攀 漀昀 洀漀氀攀挀甀氀攀猀⸀
The nucleus of a hydrogen atom (the proton) has a magnetic moment ¼ = 2.7927, and has been studied more than any other nucleus. The previous diagram may be changed to display energy differences for the proton spin states (as frequencies) by mouse clicking anywhere within it. 㰀⼀瀀㸀㰀瀀㸀
4. For spin 1/2 nuclei the energy difference between the two spin states at a given magnetic field strength will be proportional to their magnetic moments. For the four common nuclei noted above the magnetic moments are: 1H ¼ = 2.7927, 19F ¼ = 2.6273, 31P ¼ = 1.1305 & 13C ¼ = 0.7022. The following diagram gives the approximate frequencies that correspond to the spin state energy separations for each of these nuclei in an external magnetic field of 2.34 T. The formula in the colored box shows the direct correlation of frequency (energy difference) with magnetic moment (h = Planck's constant).
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2. Proton NMR Spectroscopy This important and well-established application of nuclear magnetic resonance will serve to illustrate some of the novel aspects of this method. To begin with, the nmr spectrometer must be tuned to a specific nucleus, in this case the proton. The actual procedure for obtaining the spectrum varies, but the simplest is referred to as the continuous wave (CW) method. A typical CW-spectrometer is shown in the following diagram. A solution of the sample in a uniform 5 mm glass tube is oriented between the poles of a powerful magnet, and is spun to average any magnetic field variations, as well as tube imperfections. Radio frequency radiation of appropriate energy is broadcast into the sample from an antenna coil (colored red). A receiver coil surrounds the sample tube, and emission of absorbed rf energy is monitored by dedicated electronic devices and a computer. An nmr spectrum is acquired by varying or sweeping the magnetic field over a small range while observing the rf signal from the sample. An equally effective technique is to vary the frequency of the rf radiation while holding the external field constant.㰀⼀瀀㸀㰀瀀㸀 For a description of the pulse Fourier transform technique, preferred by most spectroscopists over the older CW method, Click Here.
As an example, consider a sample of water in a 2.3487 T external magnetic field, irradiated by 100 MHz radiation. If the magnetic field is smoothly increased to 2.3488 T, the hydrogen nuclei of the water molecules will at some point absorb rf energy and a resonance signal will appear. An animation showing this may be activated by clicking the Show Field Sweep button. The field sweep will be repeated three times, and the resulting resonance trace is colored red. For visibility, the water proton signal displayed in the animation is much broader than it would be in an actual experiment.
匀椀渀挀攀 瀀爀漀琀漀渀猀 愀氀氀 栀愀瘀攀 琀栀攀 猀愀洀攀 洀愀最渀攀琀椀挀 洀漀洀攀渀琀Ⰰ 眀攀 洀椀最栀琀 攀砀瀀攀挀琀 愀氀氀 栀礀搀爀漀最攀渀 愀琀漀洀猀 琀漀 最椀瘀攀 爀攀猀漀渀愀渀挀攀 猀椀最渀愀氀猀 愀琀 琀栀攀 猀愀洀攀 昀椀攀氀搀 ⼀ 昀爀攀焀甀攀渀挀礀 瘀愀氀甀攀猀⸀ 䘀漀爀琀甀渀愀琀攀氀礀 昀漀爀 挀栀攀洀椀猀琀爀礀 愀瀀瀀氀椀挀愀琀椀漀渀猀Ⰰ 琀栀椀猀 椀猀 渀漀琀 琀爀甀攀⸀ 䈀礀 挀氀椀挀欀椀渀最 琀栀攀 匀栀漀眀 䐀椀昀昀攀爀攀渀琀 倀爀漀琀漀渀猀 戀甀琀琀漀渀 甀渀搀攀爀 琀栀攀 搀椀愀最爀愀洀Ⰰ 愀 渀甀洀戀攀爀 漀昀 爀攀瀀爀攀猀攀渀琀愀琀椀瘀攀 瀀爀漀琀漀渀 猀椀最渀愀氀猀 眀椀氀氀 戀攀 搀椀猀瀀氀愀礀攀搀 漀瘀攀爀 琀栀攀 猀愀洀攀 洀愀最渀攀琀椀挀 昀椀攀氀搀 爀愀渀最攀⸀ 䤀琀 椀猀 渀漀琀 瀀漀猀猀椀戀氀攀Ⰰ 漀昀 挀漀甀爀猀攀Ⰰ 琀漀 攀砀愀洀椀渀攀 椀猀漀氀愀琀攀搀 瀀爀漀琀漀渀猀 椀渀 琀栀攀 猀瀀攀挀琀爀漀洀攀琀攀爀 搀攀猀挀爀椀戀攀搀 愀戀漀瘀攀㬀 戀甀琀 昀爀漀洀 椀渀搀攀瀀攀渀搀攀渀琀 洀攀愀猀甀爀攀洀攀渀琀 愀渀搀 挀愀氀挀甀氀愀琀椀漀渀 椀琀 栀愀猀 戀攀攀渀 搀攀琀攀爀洀椀渀攀搀 琀栀愀琀 愀 渀愀欀攀搀 瀀爀漀琀漀渀 眀漀甀氀搀 爀攀猀漀渀愀琀攀 愀琀 愀 氀漀眀攀爀 昀椀攀氀搀 猀琀爀攀渀最琀栀 琀栀愀渀 琀栀攀 渀甀挀氀攀椀 漀昀 挀漀瘀愀氀攀渀琀氀礀 戀漀渀搀攀搀 栀礀搀爀漀最攀渀猀⸀ 圀椀琀栀 琀栀攀 攀砀挀攀瀀琀椀漀渀 漀昀 眀愀琀攀爀Ⰰ 挀栀氀漀爀漀昀漀爀洀 愀渀搀 猀甀氀昀甀爀椀挀 愀挀椀搀Ⰰ 眀栀椀挀栀 愀爀攀 攀砀愀洀椀渀攀搀 愀猀 氀椀焀甀椀搀猀Ⰰ 愀氀氀 琀栀攀 漀琀栀攀爀 挀漀洀瀀漀甀渀搀猀 愀爀攀 洀攀愀猀甀爀攀搀 愀猀 最愀猀攀猀⸀
圀栀礀 猀栀漀甀氀搀 琀栀攀 瀀爀漀琀漀渀 渀甀挀氀攀椀 椀渀 搀椀昀昀攀爀攀渀琀 挀漀洀瀀漀甀渀搀猀 戀攀栀愀瘀攀 搀椀昀昀攀爀攀渀琀氀礀 椀渀 琀栀攀 渀洀爀 攀砀瀀攀爀椀洀攀渀琀 㼀
The answer to this question lies with the electron(s) surrounding the proton in covalent compounds and ions. Since electrons are charged particles, they move in response to the external magnetic field (Bo) so as to generate a secondary field that opposes the much stronger applied field. This secondary field shields the nucleus from the applied field, so Bo must be increased in order to achieve resonance (absorption of rf energy). As illustrated in the drawing on the right, Bo must be increased to compensate for the induced shielding field. In the upper diagram, those compounds that give resonance signals at the higher field side of the diagram (CH4, HCl, HBr and HI) have proton nuclei that are more shielded than those on the lower field (left) side of the diagram. 㰀⼀瀀㸀㰀瀀㸀吀栀攀 洀愀最渀攀琀椀挀 昀椀攀氀搀 爀愀渀最攀 搀椀猀瀀氀愀礀攀搀 椀渀 琀栀攀 愀戀漀瘀攀 搀椀愀最爀愀洀 椀猀 瘀攀爀礀 猀洀愀氀氀 挀漀洀瀀愀爀攀搀 眀椀琀栀 琀栀攀 愀挀琀甀愀氀 昀椀攀氀搀 猀琀爀攀渀最琀栀 ⠀漀渀氀礀 愀戀漀甀琀 ⸀ 㐀㈀─⤀⸀ 䤀琀 椀猀 挀甀猀琀漀洀愀爀礀 琀漀 爀攀昀攀爀 琀漀 猀洀愀氀氀 椀渀挀爀攀洀攀渀琀猀 猀甀挀栀 愀猀 琀栀椀猀 椀渀 甀渀椀琀猀 漀昀 瀀愀爀琀猀 瀀攀爀 洀椀氀氀椀漀渀 ⠀瀀瀀洀⤀⸀ 吀栀攀 搀椀昀昀攀爀攀渀挀攀 戀攀琀眀攀攀渀 ㈀⸀㌀㐀㠀㜀 吀 愀渀搀 ㈀⸀㌀㐀㠀㠀 吀 椀猀 琀栀攀爀攀昀漀爀攀 愀戀漀甀琀 㐀㈀ 瀀瀀洀⸀ 䤀渀猀琀攀愀搀 漀昀 搀攀猀椀最渀愀琀椀渀最 愀 爀愀渀最攀 漀昀 渀洀爀 猀椀最渀愀氀猀 椀渀 琀攀爀洀猀 漀昀 洀愀最渀攀琀椀挀 昀椀攀氀搀 搀椀昀昀攀爀攀渀挀攀猀 ⠀愀猀 愀戀漀瘀攀⤀Ⰰ 椀琀 椀猀 洀漀爀攀 挀漀洀洀漀渀 琀漀 甀猀攀 愀 昀爀攀焀甀攀渀挀礀 猀挀愀氀攀Ⰰ 攀瘀攀渀 琀栀漀甀最栀 琀栀攀 猀瀀攀挀琀爀漀洀攀琀攀爀 洀愀礀 漀瀀攀爀愀琀攀 戀礀 猀眀攀攀瀀椀渀最 琀栀攀 洀愀最渀攀琀椀挀 昀椀攀氀搀⸀ 唀猀椀渀最 琀栀椀猀 琀攀爀洀椀渀漀氀漀最礀Ⰰ 眀攀 眀漀甀氀搀 昀椀渀搀 琀栀愀琀 愀琀 ㈀⸀㌀㐀 吀 琀栀攀 瀀爀漀琀漀渀 猀椀最渀愀氀猀 猀栀漀眀渀 愀戀漀瘀攀 攀砀琀攀渀搀 漀瘀攀爀 愀 㐀Ⰰ㈀ 䠀稀 爀愀渀最攀 ⠀昀漀爀 愀 䴀䠀稀 爀昀 昀爀攀焀甀攀渀挀礀Ⰰ 㐀㈀ 瀀瀀洀 椀猀 㐀Ⰰ㈀ 䠀稀⤀⸀ 䴀漀猀琀 漀爀最愀渀椀挀 挀漀洀瀀漀甀渀搀猀 攀砀栀椀戀椀琀 瀀爀漀琀漀渀 爀攀猀漀渀愀渀挀攀猀 琀栀愀琀 昀愀氀氀 眀椀琀栀椀渀 愀 ㈀ 瀀瀀洀 爀愀渀最攀 ⠀琀栀攀 猀栀愀搀攀搀 愀爀攀愀⤀Ⰰ 愀渀搀 椀琀 椀猀 琀栀攀爀攀昀漀爀攀 渀攀挀攀猀猀愀爀礀 琀漀 甀猀攀 瘀攀爀礀 猀攀渀猀椀琀椀瘀攀 愀渀搀 瀀爀攀挀椀猀攀 猀瀀攀挀琀爀漀洀攀琀攀爀猀 琀漀 爀攀猀漀氀瘀攀 猀琀爀甀挀琀甀爀愀氀氀礀 搀椀猀琀椀渀挀琀 猀攀琀猀 漀昀 栀礀搀爀漀最攀渀 愀琀漀洀猀 眀椀琀栀椀渀 琀栀椀猀 渀愀爀爀漀眀 爀愀渀最攀⸀ 䤀渀 琀栀椀猀 爀攀猀瀀攀挀琀 椀琀 洀椀最栀琀 戀攀 渀漀琀攀搀 琀栀愀琀 琀栀攀 搀攀琀攀挀琀椀漀渀 漀昀 愀 瀀愀爀琀ⴀ瀀攀爀ⴀ洀椀氀氀椀漀渀 搀椀昀昀攀爀攀渀挀攀 椀猀 攀焀甀椀瘀愀氀攀渀琀 琀漀 搀攀琀攀挀琀椀渀最 愀 洀椀氀氀椀洀攀琀攀爀 搀椀昀昀攀爀攀渀挀攀 椀渀 搀椀猀琀愀渀挀攀猀 漀昀 欀椀氀漀洀攀琀攀爀⸀
䤀 眀愀猀 戀漀爀渀 㤀㌀㌀ 椀渀 圀椀渀琀攀爀琀栀甀爀Ⰰ 匀眀椀琀稀攀爀氀愀渀搀Ⰰ 眀栀攀爀攀 漀甀爀 愀渀挀攀猀琀漀爀猀 爀攀猀椀搀攀搀 愀琀 氀攀愀猀琀 猀椀渀挀攀 琀栀攀 㔀琀栀 挀攀渀琀甀爀礀⸀ 圀攀 氀椀瘀攀搀 椀渀 愀 栀漀洀攀 戀甀椀氀琀 椀渀 㠀㤀㠀 戀礀 洀礀 最爀愀渀搀昀愀琀栀攀爀Ⰰ 愀 洀攀爀挀栀愀渀琀⸀ 䴀礀 昀愀琀栀攀爀Ⰰ 刀漀戀攀爀琀 䔀爀渀猀琀Ⰰ 眀愀猀 琀攀愀挀栀椀渀最 愀猀 愀渀 愀爀挀栀椀琀攀挀琀 愀琀 琀栀攀 琀攀挀栀渀椀挀愀氀 栀椀最栀 猀挀栀漀漀氀 漀昀 漀甀爀 挀椀琀礀⸀ 䤀 栀愀搀 琀栀攀 最爀攀愀琀 氀甀挀欀 琀漀 最爀漀眀 甀瀀Ⰰ 琀漀最攀琀栀攀爀 眀椀琀栀 琀眀漀 猀椀猀琀攀爀猀Ⰰ 椀渀 愀 琀漀眀渀 琀栀愀琀 挀漀洀戀椀渀攀搀 椀渀 愀 甀渀椀焀甀攀 眀愀礀 愀爀琀椀猀琀椀挀 愀渀搀 椀渀搀甀猀琀爀椀漀甀猀 愀挀琀椀瘀椀琀椀攀猀⸀䤀渀瘀愀氀甀愀戀氀攀 愀爀琀 挀漀氀氀攀挀琀椀漀渀猀 愀渀搀 愀 猀洀愀氀氀 戀甀琀 昀椀爀猀琀 爀愀渀欀 猀礀洀瀀栀漀渀礀 漀爀挀栀攀猀琀爀愀 挀愀爀爀礀 琀栀攀 昀愀洀攀 漀昀 圀椀渀琀攀爀琀栀甀爀 昀愀爀 愀挀爀漀猀猀 琀栀攀 戀漀爀搀攀爀猀 漀昀 匀眀椀琀稀攀爀氀愀渀搀⸀ 伀渀 琀栀攀 漀琀栀攀爀 栀愀渀搀Ⰰ 椀渀搀甀猀琀爀椀攀猀 瀀爀漀搀甀挀椀渀最 栀攀愀瘀礀 洀愀挀栀椀渀攀爀礀Ⰰ 氀椀欀攀 䐀椀攀猀攀氀 洀漀琀漀爀猀 愀渀搀 爀愀椀氀眀愀礀 攀渀最椀渀攀猀Ⰰ 瀀爀漀瘀椀搀攀搀 琀栀攀 挀漀洀洀攀爀挀椀愀氀 戀愀猀椀猀 漀昀 瀀爀漀猀瀀攀爀椀琀礀⸀
䤀 猀漀漀渀 戀攀挀愀洀攀 椀渀琀攀爀攀猀琀攀搀 椀渀 戀漀琀栀 猀椀搀攀猀⸀ 倀氀愀礀椀渀最 琀栀攀 瘀椀漀氀漀渀挀攀氀氀漀 戀爀漀甀最栀琀 洀攀 椀渀琀漀 渀甀洀攀爀漀甀猀 挀栀愀洀戀攀爀 愀渀搀 挀栀甀爀挀栀 洀甀猀椀挀 攀渀猀攀洀戀氀攀猀Ⰰ 愀渀搀 猀琀椀洀甀氀愀琀攀搀 洀礀 椀渀琀攀爀攀猀琀 椀渀 洀甀猀椀挀愀氀 挀漀洀瀀漀猀椀琀椀漀渀 琀栀愀琀 䤀 琀爀椀攀搀 攀砀琀攀渀猀椀瘀攀氀礀 眀栀椀氀攀 椀渀 栀椀最栀 猀挀栀漀漀氀⸀ 䄀琀 琀栀攀 愀最攀 漀昀 ㌀Ⰰ 䤀 昀漀甀渀搀 椀渀 琀栀攀 愀琀琀椀挀 愀 挀愀猀攀 昀椀氀氀攀搀 眀椀琀栀 挀栀攀洀椀挀愀氀猀Ⰰ 爀攀洀愀椀渀搀攀爀猀 漀昀 愀渀 甀渀挀氀攀 眀栀漀 搀椀攀搀 椀渀 㤀㈀㌀ 愀渀搀 眀愀猀Ⰰ 愀猀 愀 洀攀琀愀氀氀甀爀最椀挀愀氀 攀渀最椀渀攀攀爀Ⰰ 椀渀琀攀爀攀猀琀攀搀 椀渀 挀栀攀洀椀猀琀爀礀 愀渀搀 瀀栀漀琀漀最爀愀瀀栀礀⸀ 䤀 戀攀挀愀洀攀 愀氀洀漀猀琀 椀洀洀攀搀椀愀琀攀氀礀 昀愀猀挀椀渀愀琀攀搀 戀礀 琀栀攀 瀀漀猀猀椀戀椀氀椀琀椀攀猀 漀昀 琀爀礀椀渀最 漀甀琀 愀氀氀 挀漀渀挀攀椀瘀愀戀氀攀 爀攀愀挀琀椀漀渀猀 眀椀琀栀 琀栀攀洀Ⰰ 猀漀洀攀 氀攀愀搀椀渀最 琀漀 攀砀瀀氀漀猀椀漀渀猀Ⰰ 漀琀栀攀爀猀 琀漀 甀渀戀攀愀爀愀戀氀攀 瀀漀椀猀漀渀椀渀最 漀昀 琀栀攀 愀椀爀 椀渀 漀甀爀 栀漀甀猀攀Ⰰ 昀爀椀最栀琀攀渀椀渀最 洀礀 瀀愀爀攀渀琀猀⸀ 䠀漀眀攀瘀攀爀Ⰰ 䤀 猀甀爀瘀椀瘀攀搀 愀渀搀 猀琀愀爀琀攀搀 琀漀 爀攀愀搀 愀氀氀 挀栀攀洀椀猀琀爀礀 戀漀漀欀猀 琀栀愀琀 䤀 挀漀甀氀搀 最攀琀 愀 栀愀渀搀 漀渀Ⰰ 昀椀爀猀琀 猀漀洀攀 㤀琀栀 挀攀渀琀甀爀礀 戀漀漀欀猀 昀爀漀洀 漀甀爀 栀漀洀攀 氀椀戀爀愀爀礀 琀栀愀琀 搀椀搀 渀漀琀 瀀爀漀瘀椀搀攀 洀甀挀栀 爀攀氀椀愀戀氀攀 椀渀昀漀爀洀愀琀椀漀渀Ⰰ 愀渀搀 琀栀攀渀 䤀 攀洀瀀琀椀攀搀 琀栀攀 爀愀琀栀攀爀 攀砀琀攀渀猀椀瘀攀 挀椀琀礀 氀椀戀爀愀爀礀⸀ 匀漀漀渀Ⰰ 䤀 欀渀攀眀 琀栀愀琀 䤀 眀漀甀氀搀 戀攀挀漀洀攀 愀 挀栀攀洀椀猀琀Ⰰ 爀愀琀栀攀爀 琀栀愀渀 愀 挀漀洀瀀漀猀攀爀⸀ 䤀 眀愀渀琀攀搀 琀漀 甀渀搀攀爀猀琀愀渀搀 琀栀攀 猀攀挀爀攀琀猀 戀攀栀椀渀搀 洀礀 挀栀攀洀椀挀愀氀 攀砀瀀攀爀椀洀攀渀琀猀 愀渀搀 戀攀栀椀渀搀 琀栀攀 瀀爀漀挀攀猀猀攀猀 椀渀 渀愀琀甀爀攀⸀
吀栀甀猀Ⰰ 愀昀琀攀爀 昀椀渀椀猀栀椀渀最 栀椀最栀 猀挀栀漀漀氀Ⰰ 䤀 猀琀愀爀琀攀搀 眀椀琀栀 栀椀最栀 攀砀瀀攀挀琀愀琀椀漀渀猀 愀渀搀 攀渀琀栀甀猀椀愀猀洀 琀漀 猀琀甀搀礀 挀栀攀洀椀猀琀爀礀 愀琀 琀栀攀 昀愀洀漀甀猀 匀眀椀猀猀 䘀攀搀攀爀愀氀 䤀渀猀琀椀琀甀琀攀 漀昀 吀攀挀栀渀漀氀漀最礀 椀渀 娀甀爀椀挀栀 ⠀䔀吀䠀ⴀ娀⤀⸀ 䤀 眀愀猀 爀愀瀀椀搀氀礀 搀椀猀愀瀀瀀漀椀渀琀攀搀 戀礀 琀栀攀 猀琀愀琀攀 漀昀 挀栀攀洀椀猀琀爀礀 椀渀 琀栀攀 攀愀爀氀礀 昀椀昀琀椀攀猀 愀猀 椀琀 眀愀猀 琀愀甀最栀琀 愀琀 䔀吀䠀ⴀ娀㬀 眀攀 猀琀甀搀攀渀琀猀 栀愀搀 琀漀 洀攀洀漀爀椀稀攀 椀渀挀漀甀渀琀愀戀氀攀 昀愀挀琀猀 琀栀愀琀 攀瘀攀渀 琀栀攀 瀀爀漀昀攀猀猀漀爀猀 搀椀搀 渀漀琀 甀渀搀攀爀猀琀愀渀搀⸀ 䄀 最漀漀搀 洀攀洀漀爀礀 渀漀琀 椀洀瀀攀挀挀愀戀氀攀 氀漀最椀挀 眀愀猀 漀渀 搀攀洀愀渀搀⸀ 吀栀攀 瀀栀礀猀椀挀愀氀 挀栀攀洀椀猀琀爀礀 氀攀挀琀甀爀攀猀 搀椀搀 渀漀琀 爀攀瘀攀愀氀 洀甀挀栀 椀渀猀椀最栀琀 攀椀琀栀攀爀Ⰰ 琀栀攀礀 眀攀爀攀 氀椀洀椀琀攀搀 樀甀猀琀 琀漀 挀氀愀猀猀椀挀愀氀 琀栀攀爀洀漀搀礀渀愀洀椀挀猀⸀ 吀栀甀猀Ⰰ 䤀 栀愀搀 琀漀 挀漀渀琀椀渀甀攀Ⰰ 猀椀洀椀氀愀爀 愀猀 椀渀 栀椀最栀 猀挀栀漀漀氀Ⰰ 琀漀 最愀椀渀 猀漀洀攀 搀攀挀攀渀琀 挀栀攀洀椀挀愀氀 欀渀漀眀氀攀搀最攀 戀礀 爀攀愀搀椀渀最⸀ 䄀 戀漀漀欀 昀爀漀洀 眀栀椀挀栀 䤀 氀攀愀爀渀攀搀 愀 氀漀琀 愀琀 琀栀愀琀 琀椀洀攀 眀愀猀 ∀吀栀攀漀爀攀琀椀挀愀氀 䌀栀攀洀椀猀琀爀礀∀ 戀礀 匀⸀ 䜀氀愀猀猀琀漀渀攀⸀ 䤀琀 爀攀瘀攀愀氀攀搀 琀漀 洀攀 琀栀攀 昀甀渀搀愀洀攀渀琀愀氀猀 漀昀 焀甀愀渀琀甀洀 洀攀挀栀愀渀椀挀猀Ⰰ 猀瀀攀挀琀爀漀猀挀漀瀀礀Ⰰ 猀琀愀琀椀猀琀椀挀愀氀 洀攀挀栀愀渀椀挀猀Ⰰ 愀渀搀 猀琀愀琀椀猀琀椀挀愀氀 琀栀攀爀洀漀搀礀渀愀洀椀挀猀Ⰰ 猀甀戀樀攀挀琀猀 琀栀愀琀 眀攀爀攀 渀攀瘀攀爀 攀瘀攀渀 洀攀渀琀椀漀渀攀搀 椀渀 氀攀挀琀甀爀攀猀Ⰰ 攀砀挀攀瀀琀 椀渀 愀 瘀漀氀甀渀琀愀爀礀 愀渀搀 瘀攀爀礀 攀砀挀攀氀氀攀渀琀 氀攀挀琀甀爀攀 挀漀甀爀猀攀 最椀瘀攀渀 戀礀 琀栀攀 礀漀甀渀最 攀渀琀栀甀猀椀愀猀琀椀挀 倀爀漀昀攀猀猀漀爀 䠀愀渀猀 䠀⸀䜀ﰀ渀琀栀愀爀搀 眀栀漀 栀愀搀 猀琀甀搀椀攀搀 挀栀攀洀椀猀琀爀礀 愀渀搀 瀀栀礀猀椀挀猀 椀渀 瀀愀爀愀氀氀攀氀⸀
䤀琀 眀愀猀 挀氀攀愀爀 琀漀 洀攀Ⰰ 愀昀琀攀爀 洀礀 搀椀瀀氀漀洀愀 愀猀 愀 ∀䐀椀瀀氀漀洀椀攀爀琀攀爀 䤀渀最攀渀椀攀甀爀 䌀栀攀洀椀欀攀爀∀ 愀渀搀 猀漀洀攀 攀砀琀攀渀猀椀瘀攀 洀椀氀椀琀愀爀礀 猀攀爀瘀椀挀攀Ⰰ 䤀 栀愀搀 琀漀 猀琀愀爀琀 愀 倀栀䐀 琀栀攀猀椀猀 椀渀 琀栀攀 氀愀戀漀爀愀琀漀爀礀 漀昀 倀爀漀昀攀猀猀漀爀 䜀ﰀ渀琀栀愀爀搀⸀ 䘀漀爀琀甀渀愀琀攀氀礀Ⰰ 栀攀 愀挀挀攀瀀琀攀搀 洀攀 愀渀搀 愀猀猀漀挀椀愀琀攀搀 洀攀 眀椀琀栀 愀 礀漀甀渀最 洀漀猀琀 戀爀椀氀氀椀愀渀琀 猀挀椀攀渀琀椀猀琀 䠀愀渀猀 倀爀椀洀愀猀Ⰰ 眀栀漀 渀攀瘀攀爀 眀攀渀琀 琀栀爀漀甀最栀 愀渀礀 昀漀爀洀愀氀 猀琀甀搀椀攀猀 戀甀琀 渀攀瘀攀爀琀栀攀氀攀猀猀 愀挀焀甀椀爀攀搀 爀愀瀀椀搀氀礀 眀栀愀琀攀瘀攀爀 栀攀 渀攀攀搀攀搀 昀漀爀 栀椀猀 眀漀爀欀 琀栀愀琀 眀愀猀 琀栀攀渀 挀漀渀挀攀爀渀攀搀 眀椀琀栀 栀椀最栀 爀攀猀漀氀甀琀椀漀渀 渀甀挀氀攀愀爀 洀愀最渀攀琀椀挀 爀攀猀漀渀愀渀挀攀 ⠀一䴀刀⤀Ⰰ 愀 昀椀攀氀搀 椀渀 椀琀猀 椀渀昀愀渀挀礀 愀琀 琀栀愀琀 琀椀洀攀⸀ 䴀甀挀栀 漀昀 栀椀猀 愀渀搀 愀氀猀漀 洀礀 琀椀洀攀 眀愀猀 猀瀀攀渀琀 漀渀 搀攀猀椀最渀椀渀最 愀渀搀 戀甀椀氀搀椀渀最 愀搀瘀愀渀挀攀搀 攀氀攀挀琀爀漀渀椀挀 攀焀甀椀瀀洀攀渀琀 昀漀爀 椀洀瀀爀漀瘀攀搀 一䴀刀 猀瀀攀挀琀爀漀洀攀琀攀爀猀⸀ 䤀渀 瀀愀爀愀氀氀攀氀Ⰰ 眀攀 搀攀瘀攀氀漀瀀攀搀 琀栀攀 琀栀攀漀爀攀琀椀挀愀氀 戀愀挀欀最爀漀甀渀搀 昀漀爀 琀栀攀 攀砀瀀攀爀椀洀攀渀琀猀 眀攀 栀愀搀 椀渀 洀椀渀搀 愀猀 眀攀氀氀 愀猀 昀漀爀 琀栀攀 漀瀀琀椀洀甀洀 瀀攀爀昀漀爀洀愀渀挀攀 漀昀 琀栀攀 椀渀猀琀爀甀洀攀渀琀猀⸀ 匀椀最渀愀氀ⴀ琀漀ⴀ渀漀椀猀攀 爀愀琀椀漀 挀愀氀挀甀氀愀琀椀漀渀猀 愀渀搀 漀瀀琀椀洀椀稀愀琀椀漀渀猀 眀攀爀攀 搀愀椀氀礀 爀漀甀琀椀渀攀 愀猀 一䴀刀 猀甀昀昀攀爀猀 昀爀漀洀 愀 搀椀猀愀瀀瀀漀椀渀琀椀渀最氀礀 氀漀眀 猀攀渀猀椀琀椀瘀椀琀礀 琀栀愀琀 猀攀瘀攀爀攀氀礀 氀椀洀椀琀猀 椀琀猀 愀瀀瀀氀椀挀愀琀椀漀渀猀⸀ 䠀愀渀猀 倀爀椀洀愀猀 搀攀瘀攀氀漀瀀攀搀 愀渀搀 愀渀愀氀礀稀攀搀 昀椀攀氀搀 洀漀搀甀氀愀琀椀漀渀 琀攀挀栀渀椀焀甀攀猀Ⰰ 挀漀渀猀琀爀甀挀琀攀搀 愀 昀椀攀氀搀 昀爀攀焀甀攀渀挀礀 氀漀挀欀 猀礀猀琀攀洀Ⰰ 愀渀搀 挀漀渀琀爀椀戀甀琀攀搀 愀 渀攀眀 搀攀猀椀最渀 漀昀 猀栀愀瀀攀搀 瀀漀氀攀 挀愀瀀猀 昀漀爀 琀栀攀 攀氀攀挀琀爀漀洀愀最渀攀琀 琀栀愀琀 眀愀猀 猀甀瀀瀀漀猀攀搀 琀漀 搀攀氀椀瘀攀爀 愀渀 攀砀琀爀攀洀攀氀礀 栀漀洀漀最攀渀攀漀甀猀 洀愀最渀攀琀椀挀 昀椀攀氀搀⸀ 吀栀攀猀攀 搀攀瘀攀氀漀瀀洀攀渀琀猀 氀攀搀 琀漀 琀眀漀 琀礀瀀攀猀 漀昀 猀瀀攀挀琀爀漀洀攀琀攀爀猀 琀栀愀琀 眀攀爀攀 愀搀漀瀀琀攀搀 戀礀 吀爀ﰀ戀ⴀ吀甀戀攀爀Ⰰ 愀 匀眀椀猀猀 攀氀攀挀琀爀漀渀椀挀猀 挀漀洀瀀愀渀礀Ⰰ 愀渀搀 猀漀氀搀 愀氀氀 漀瘀攀爀 䔀甀爀漀瀀攀⸀ 䰀愀琀攀爀 椀渀 㤀㘀㔀Ⰰ 吀爀ﰀ戀ⴀ吀甀戀攀爀 眀愀猀 搀椀猀猀漀氀瘀攀搀Ⰰ 愀渀搀 琀栀攀 一䴀刀 猀瀀攀挀琀爀漀猀挀漀瀀礀 猀攀挀琀椀漀渀 氀攀搀 琀漀 琀栀攀 昀漀甀渀搀愀琀椀漀渀 漀昀 匀瀀攀挀琀爀漀猀瀀椀渀 䄀䜀 琀栀愀琀 椀猀Ⰰ 琀漀最攀琀栀攀爀 眀椀琀栀 䈀爀甀欀攀爀 䄀渀愀氀礀琀椀猀挀栀攀 䴀攀猀猀琀攀挀栀渀椀欀Ⰰ 渀漀眀愀搀愀礀猀 琀栀攀 眀漀爀氀搀 氀攀愀搀椀渀最 瀀爀漀搀甀挀攀爀 漀昀 一䴀刀 猀瀀攀挀琀爀漀洀攀琀攀爀猀⸀
䴀礀 漀眀渀 眀漀爀欀 搀攀愀氀琀 眀椀琀栀 琀栀攀 挀漀渀猀琀爀甀挀琀椀漀渀 漀昀 栀椀最栀 猀攀渀猀椀琀椀瘀椀琀礀 爀愀搀椀漀 昀爀攀焀甀攀渀挀礀 瀀爀攀愀洀瀀氀椀昀椀攀爀猀 愀渀搀 椀渀 瀀愀爀琀椀挀甀氀愀爀 栀椀最栀 猀攀渀猀椀琀椀瘀椀琀礀 瀀爀漀戀攀 愀猀猀攀洀戀氀椀攀猀Ⰰ 椀渀椀琀椀愀氀氀礀 昀漀爀 愀 ㈀㔀 䴀䠀稀Ⰰ 氀愀琀攀爀 昀漀爀 愀 㜀㔀 䴀䠀稀 瀀爀漀琀漀渀 爀攀猀漀渀愀渀挀攀 猀瀀攀挀琀爀漀洀攀琀攀爀⸀ 伀渀 琀栀攀 琀栀攀漀爀攀琀椀挀愀氀 猀椀搀攀Ⰰ 䤀 眀愀猀 挀漀渀挀攀爀渀攀搀 眀椀琀栀 猀琀漀挀栀愀猀琀椀挀 爀攀猀漀渀愀渀挀攀⸀ 吀栀攀 最漀愀氀 猀攀琀 戀礀 䠀愀渀猀 倀爀椀洀愀猀 眀愀猀 琀栀攀 甀猀愀最攀 漀昀 爀愀渀搀漀洀 渀漀椀猀攀 昀漀爀 琀栀攀 攀砀挀椀琀愀琀椀漀渀 漀昀 渀甀挀氀攀愀爀 洀愀最渀攀琀椀挀 爀攀猀漀渀愀渀挀攀Ⰰ 昀漀氀氀漀眀椀渀最 琀栀攀 昀愀洀漀甀猀 挀漀渀挀攀瀀琀猀 漀昀 一漀爀戀攀爀琀 圀椀攀渀攀爀 昀漀爀 琀栀攀 猀琀漀挀栀愀猀琀椀挀 琀攀猀琀椀渀最 漀昀 渀漀渀ⴀ氀椀渀攀愀爀 猀礀猀琀攀洀猀⸀ 吀栀攀 琀栀攀漀爀攀琀椀挀愀氀 琀爀攀愀琀洀攀渀琀 眀愀猀 戀愀猀攀搀 漀渀 愀 嘀漀氀琀攀爀爀愀 昀甀渀挀琀椀漀渀愀氀 攀砀瀀愀渀猀椀漀渀 甀猀椀渀最 漀爀琀栀漀最漀渀愀氀 猀琀漀挀栀愀猀琀椀挀 瀀漀氀礀渀漀洀椀愀氀猀⸀ 䤀 琀爀椀攀搀 椀渀 瀀愀爀琀椀挀甀氀愀爀 琀漀 搀攀猀椀最渀 愀 猀挀栀攀洀攀 漀昀 栀漀洀漀渀甀挀氀攀愀爀 戀爀漀愀搀戀愀渀搀 搀攀挀漀甀瀀氀椀渀最 琀漀 猀椀洀瀀氀椀昀礀 瀀爀漀琀漀渀 爀攀猀漀渀愀渀挀攀 猀瀀攀挀琀爀愀⸀ 䈀礀 愀瀀瀀氀礀椀渀最 愀 猀琀漀挀栀愀猀琀椀挀 猀攀焀甀攀渀挀攀 眀椀琀栀 愀 猀栀愀瀀攀搀 瀀漀眀攀爀 猀瀀攀挀琀爀愀氀 搀攀渀猀椀琀礀 琀栀愀琀 栀愀猀 愀 栀漀氀攀 愀琀 琀栀攀 漀戀猀攀爀瘀愀琀椀漀渀 昀爀攀焀甀攀渀挀礀Ⰰ 愀氀氀 攀砀琀爀愀渀攀漀甀猀 瀀爀漀琀漀渀猀 猀栀漀甀氀搀 戀攀 搀攀挀漀甀瀀氀攀搀 眀椀琀栀漀甀琀 瀀攀爀琀甀爀戀椀渀最 琀栀攀 漀戀猀攀爀瘀攀搀 瀀爀漀琀漀渀 猀瀀椀渀⸀ 吀栀攀 琀栀攀漀爀攀琀椀挀愀氀 搀椀昀昀挀甀氀琀椀攀猀 眀攀爀攀 洀愀椀渀氀礀 挀漀渀挀攀爀渀攀搀 眀椀琀栀 琀栀攀 挀漀洀瀀甀琀愀琀椀漀渀 漀昀 琀栀攀 爀攀猀瀀漀渀猀攀 琀漀 渀漀渀眀栀椀琀攀 渀漀椀猀攀⸀ 䔀砀瀀攀爀椀洀攀渀琀猀 眀攀爀攀 渀漀琀 愀琀琀攀洀瀀琀攀搀 愀琀 琀栀愀琀 琀椀洀攀Ⰰ 眀攀 搀椀搀 渀漀琀 戀攀氀椀攀瘀攀 椀渀 琀栀攀 甀猀攀昀甀氀渀攀猀猀 漀昀 琀栀攀 挀漀渀挀攀瀀琀 愀渀礀眀愀礀Ⰰ 愀渀搀 䤀 昀椀渀椀猀栀攀搀 洀礀 琀栀攀猀椀猀 椀渀 㤀㘀㈀ 眀椀琀栀 愀 昀攀攀氀椀渀最 氀椀欀攀 愀渀 愀爀琀椀猀琀 戀愀氀愀渀挀椀渀最 漀渀 愀 栀椀最栀 爀漀瀀攀 眀椀琀栀漀甀琀 愀渀礀 椀渀琀攀爀攀猀琀攀搀 猀瀀攀挀琀愀琀漀爀猀⸀
䤀 琀栀甀猀 搀攀挀椀搀攀搀 琀漀 氀攀愀瘀攀 琀栀攀 甀渀椀瘀攀爀猀椀琀礀 昀漀爀攀瘀攀爀 愀渀搀 琀爀椀攀搀 琀漀 昀椀渀搀 愀渀 椀渀搀甀猀琀爀椀愀氀 樀漀戀 椀渀 琀栀攀 唀渀椀琀攀搀 匀琀愀琀攀猀⸀ 䄀洀漀渀最 渀甀洀攀爀漀甀猀 漀昀昀攀爀猀Ⰰ 䤀 搀攀挀椀搀攀搀 昀漀爀 嘀愀爀椀愀渀 䄀猀猀漀挀椀愀琀攀猀 椀渀 倀愀氀漀 䄀氀琀漀 眀栀攀爀攀 昀愀洀漀甀猀 猀挀椀攀渀琀椀猀琀猀Ⰰ 氀椀欀攀 圀攀猀琀漀渀 䄀⸀ 䄀渀搀攀爀猀漀渀Ⰰ 刀愀礀 䘀爀攀攀洀愀渀Ⰰ 䨀椀洀 䠀礀搀攀Ⰰ 䴀愀爀琀椀渀 倀愀挀欀愀爀搀Ⰰ 愀渀搀 䠀愀爀爀礀 圀攀愀瘀攀爀Ⰰ 眀攀爀攀 眀漀爀欀椀渀最 along similar lines as we in Zürich but with a clear commercial goal in mind. This attracted my interest, hoping to find some motivation for my own work. And indeed, I was extremely lucky. Weston Anderson was on his way to invent Fourier transform spectroscopy in order to improve the sensitivity of NMR by parallel data acquisition. After his involvement in the development of a cute mechanical device, the "wheel of fortune", to generate and detect several frequencies in parallel, he proposed to me in 1964 to try a pulse excitation experiment that indeed led to Fourier transform (FT) NMR as we know it today. The first successful experiments were done in summer 1964 while Weston Anderson was abroad on an extensive business trip. In this work I could take advantage in an optimum way of my knowledge in system theory gained during my studies with Primas and Günthard. The response to our invention was however meager. The paper that described our achievements was rejected twice by the Journal of Chemical Physics to be finally accepted and published in the Review of Scientific Instruments. Varian also resisted to build a spectrometer that incorporated the novel Fourier transform concept. It took many years before in the competitive company Bruker Analytische Messtechnik Tony Keller and his coworkers demonstrated in 1969 for the first time a commercial FT NMR spectrometer to the great amazement of Varian that had the patent rights on the invention.㰀⼀瀀㸀㰀瀀㸀 Still at Varian, I was further extending my earlier work on stochastic resonance with the introduction of heteronuclear broadband decoupling by noise irradiation, the "noise decoupling" that led to a rapid development in carbon-13 spectroscopy. It has been replaced later by the much more effcient multiple pulse schemes of Malcolm H. Levitt and Ray Freeman using composite pulses.㰀⼀瀀㸀㰀瀀㸀 Of major importance for the success of more advanced experiments and measurement techniques in NMR was the availability of small laboratory computers that could be hooked up directly to the spectrometer. During my last years at Varian (1966-68), we developed numerous computer applications in spectroscopy for automated experiments and improved data processing.㰀⼀瀀㸀㰀瀀㸀 In 1968 I returned, after an extensive trip through Asia, to Switzerland. A brief visit to Nepal started my insatiable love for Asian art. My main interest is directed towards Tibetan scroll paintings, the so-called thangkas, a unique and most exciting form of religious art with its own strict rules and nevertheless incorporating an incredible exuberance of creativity.㰀⼀瀀㸀㰀瀀㸀 Back in Switzerland, I had a chance to take over the lead of the NMR research group at the Laboratorium für Physikalische Chemie of ETH-Z after Professor Primas turned his interests more towards theoretical chemistry. Despite an initial lack of suitable instrumentation, I continued to work on methodological improvements of time-domain NMR with repetitive pulse experiments and Fourier double resonance. In addition, we performed the first pulsed time-domain chemically-induced dynamic nuclear polarization (CIDNP) experiments. We developed at that time also stochastic resonance as an alternative to pulse FT spectroscopy employing binary pseudo-random noise sequences for broadband excitation, correlating input and output noise. Similar work was done simultaneously by Prof. Reinhold Kaiser at the University of New Brunswick.㰀⼀瀀㸀㰀瀀㸀 The next fortunate event occurred in 1971 when my first graduate student, Thomas Baumann, visited the Ampere Summer School in Basko Polje, Yugoslavia, where Professor Jean Jeener proposed a simple two-pulse sequence that produces, after two-dimensional Fourier transformation, a two-dimensional (2D) spectrum. In the course of time, we recognized the importance and universality of his proposal. In my group, Enrico Bartholdi performed at first some analytical calculations to explore the features of 2D experiments. Finally in the summer of 1974, we tried our first experiments in desperate need of results to be presented at the VIth International Conference on Magnetic Resonance in Biological Systems, Kandersteg, 1974.㰀⼀瀀㸀㰀瀀㸀 At the same time, it occurred to me that the 2D spectroscopy principle could also be applied to NMR imaging, previously proposed by Paul Lauterbur. This led then to the invention of Fourier imaging on which the at present most frequently used spin-warp imaging technique relies. First experiments were done by Anil Kumar and Dieter Welti.㰀⼀瀀㸀㰀瀀㸀 From then on, the development of multi-dimensional spectroscopy went very fast, inside and outside of our research group. Prof. John S. Waugh extended it for applications to solid state resonance, and the research group of Prof. Ray Freeman, particularly Geoffrey Bodenhausen, contributed some of the first heteronuclear experiments. We started 1976 an intense collaboration, lasting for 10 years, with Professor Kurt Wüthrich of ETH-Z to develop applications of 2D spectroscopy in molecular biology. He and his research group have been responsible for most essential innovations that enabled the determination of the three-dimensional structure of biomolecules in solution.
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