A search for N2+ spectra of comet C/2002 Cl (Ikeya-Zhang)

We report low- and high-resolution spectra of comet C/2002 C1 (Ikeya-Zhang) from the McDonald Observatory. The comet has a well-developed ion tail including CO+, CO2+, CH+, and H2O+. We used our high-resolution spectra to search for N-2(+). None was detected, and we placed upper limits on N-2(+)/CO+ of 5.4x10(-4). N-2(+) was detected in the low- resolution spectra, but we show that this emission was probably telluric in origin (if cometary, we derive N-2(+)/CO+ = 5.5x10(-3), still very low). We discuss the implications for the conditions in the early solar nebula of the nondetection of N-2(+). These depend on whether the H2O ice was deposited in the amorphous or crystalline form. If H2O was deposited in its crystalline form, the detection of CO+ but not N-2(+) has implications for H2O/H-2 in the early solar nebula.