An accurate measurement of the fundamental spin-spin relaxation time (t2) comes from the amplitude of the "spin echo" as a function of delay time (t). the experiment involves a 900 pulse that rotates the spins into the x-y plane, where they precess at a range of frequencies due to the range of local fields. after the delay time t, a 180° pulse is applied so that the spins that were ahead by precessing faster are inverted to become behind the spins that precessed slower. a large-amplitude spin echo occurs at an additional delay of t, when the faster precessing spins temporarily coincide with the slower precessing spins. question 1 2 pts when the delay time between the 900 and 1800 pulses is t-5.66 ms, the spin echo (that occurs at a later time) becomes 1/e of its initial amplitude. the resulting spin-spin relaxation time is t2 d question 2 2 pts the table (pasted below) gives the amplitudes of the spin echo as a function of the delay time between 90° and 180° pulses. fitting the data to an exponential r delay(ms) 0.2 0.5 echolv) 4024 3.786 3.364 2.791 2.239 1.868 1.725 1.152 0.838 0.462 7.5 10 15 elaxation function yields a spin-spin relaxation time of ta ms