I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany.
Rev Sci Instrum. 2023 Mar 1;94(3):034705. doi: 10.1063/5.0141579.
We present a home-built chirped-pulse Fourier transform millimeter wave (CP-FTMMW) spectrometer. The setup is devoted to the sensitive recording of high-resolution molecular spectroscopy in the W band between 75 and 110 GHz. We describe the experimental setup in detail, including a characterization of the chirp excitation source, the optical beam path, and the receiver. The receiver is a further development of our 100 GHz emission spectrometer. The spectrometer is equipped with a pulsed jet expansion and a DC discharge. Spectra of methyl cyanide as well as hydrogen cyanide (HCN) and hydrogen isocyanide (HNC) products from the DC discharge of this molecule are recorded to characterize the performance of the CP-FTMMW instrument. The formation of the HCN isomer is favored by a factor of 63 with respect to HNC. Hot/cold calibration measurements enable a direct comparison of the signal and noise levels of the CP-FTMMW spectra to those of the emission spectrometer. For the CP-FTMMW instrument, we find many orders of magnitude of signal enhancement and a much stronger noise reduction due to the coherent detection scheme.
我们展示了一种自制的啁啾脉冲傅里叶变换毫米波（CP-FTMMW）光谱仪。该装置致力于在 75 至 110 GHz 的 W 波段内记录高分辨率的分子光谱，具有较高的灵敏度。我们详细描述了实验设置，包括啁啾激发源、光路和接收器的特性。接收器是我们 100GHz 发射光谱仪的进一步发展。该光谱仪配备了脉冲射流膨胀和直流放电。记录了甲基氰化物以及该分子的直流放电产生的氢氰化物（HCN）和异氰化氢（HNC）产物的光谱，以表征 CP-FTMMW 仪器的性能。与 HNC 相比，HCN 异构体的形成受到 63 倍的促进。热/冷校准测量可使 CP-FTMMW 光谱的信号和噪声水平与发射光谱的信号和噪声水平直接进行比较。对于 CP-FTMMW 仪器，由于相干检测方案，我们发现信号增强了许多数量级，噪声降低了很多。
