Sample head for nuclear resonance measurements

Claim 1

A sample head for performing nuclear magnetic resonance experiments on a first kind of nuclei ( 1 H) and, further, on a second ( 15 N, 31 P) and, alternately a third ( 31 P) kind of nuclei within a magnetic field (B), the sample head comprising: a measuring coil for interacting with a sample under analysis and for generating a nuclear magnetic resonance within said sample or for receiving a nuclear magnetic resonance signal from said sample; a first sample head terminal connected to a first end of said measuring coil for transmitting to or receiving from said measuring coil a first high-frequency signal having a first, higher frequency corresponding to a nuclear magnetic resonance frequency of said first kind of nuclei ( 1 H) within said magnetic field (B); a second sample head terminal connected to a second end of said measuring coil for transmitting to or receiving from said measuring soil a second and, alternately a third high-frequency signal having a second and, alternately a third, lower frequency corresponding to a nuclear magnetic resonance frequency of said second or third kind of nuclei ( 15 N, 31 P), respectively, within said magnetic field (B); a high frequency line connected to said measuring coil at said second end thereof, said line having an electric length which is an integer multiple of a quarter wavelength corresponding to said first, higher frequency; and switching means associated with said high-frequency line for switching said electrical length thereof from a first mode of operation for experiments where said second, lower frequency corresponding to said second kind of nuclei ( 15 N) is about one order of magnitude lower than said first, higher frequency corresponding to said first kind of nuclei ( 1 H), and said line, at said second, lower frequency, has a first electrical length such that it acts as an inductance connected in series with said measuring coil, to a second mode of operation for experiments where said third, lower frequency corresponding to said third kind of nuclei ( 31 P) is up to one half of said first, higher frequency corresponding to said first kind of nuclei ( 1 H), and said line, at said third, lower frequency, has a second electrical length such that it acts as a capacitance connected in series with said measuring coil.